List of shipwrecks in May 1917

The list of shipwrecks in May 1917 includes some ships sunk, foundered, grounded, or otherwise lost during May 1917.

1 May

 * Acacia (🇫🇷 France): World War I: The fishing vessel was sunk in the Bay of Biscay 7 nmi off the Chassiron Lighthouse, Charente-Maritime by SMU UC-72 . Her crew survived.
 * Alide ( undefined): World War I: The sailing vessel was sunk in the Atlantic Ocean off Land's End, Cornwall, United Kingdom by SMU UC-75.
 * Antigone (🇫🇷 France): World War I: The fishing vessel was sunk in the Bay of Biscay 8 nmi off the Chassiron Lighthouse by SMU UC-72 . Her crew survived.
 * SS Bagdale (1904) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 13 nmi north east of Creac'h Point, Ouessant, Finistère, France (48.68333°N, -5.13333°W) by SMU UC-66 with the loss of 23 of her crew.
 * SS Barreiro (1911) (🇵🇹 Portugal): World War I: The cargo ship was sunk in the Bay of Biscay 4 nmi off Suances, Cantabria, Spain by SMU UC-69.
 * SS British Sun (1909) ( undefined): World War I: The tanker was torpedoed and sunk in the Mediterranean Sea 230 nmi east south east of Malta by SMU UB-43 . Her crew survived.
 * SS C. A. Jacques (1909) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 26 nmi west south west of Boulogne, Pas-de-Calais, France (50.45°N, 1.06667°W) by SMU UB-18 with the loss of three of her crew.
 * Camille Amelin (🇫🇷 France): World War I: The fishing vessel was sunk in the Bay of Biscay 6 nmi off the Baleines Lighthouse, Charente-Maritime by SMU UC-72 . Her crew survived.
 * SS Dora (1900) ( undefined): World War I: The coaster was scuttled in the Irish Sea 11 nmi west of the Mull of Galloway by SMU UC-65 . Her crew survived.
 * SS Gena ( undefined: World War I: The collier was torpedoed and sunk in the North Sea off Southwold, Suffolk by a Luftstreitkräfte aircraft.
 * SS Firelight (1896) ( undefined): World War I: The cargo ship was torpedoed and sunk in the North Sea (55.01667°N, -1.35°W) by SMU UC-29 . Her crew survived.
 *  Imberhorne (🇫🇮 Finland): World War I: The full-rigged ship was sunk in the Atlantic Ocean 130 nmi north west by west of the Stags of Broadhaven, County Mayo, United Kingdom (54.11667°N, -13.06667°W) by SMU UC-73.
 * SS Ladywood (1910) ( undefined): World War I: The cargo ship was scuttled in the Atlantic Ocean 15 nmi south west of the Wolf Rock, Cornwall (49.86667°N, -5.98333°W) by SMU UB-38 . Her crew survived.
 * SS Helen (1904) ( undefined): World War I: The coaster was scuttled in the Irish Sea 11 nmi west of the Mull of Galloway, Wigtownshire by SMU UC-65 . Her crew survived.
 *  Ivrig (🇳🇴 Norway): World War I: The barque was shelled and sunk in the Irish Sea 10 nmi south west of Portpatrick, Wigtownshire by SMU UC-65 . Her crew survived.
 *  John W. Pearn ( undefined): World War I: The schooner was scuttled in the English Channel 40 nmi south south east of Start Point, Devon (49.7°N, -2.96667°W) by SMU UC-66 . Her crew survived.
 *  La Manche (🇫🇷 France): World War I: The barque was scuttled in the English Channel 8 nmi north of the Les Hanois Lighthouse, Guernsey, Channel Islands by SMU UC-66 . Her crew survived.
 * Raymond Ester (🇫🇷 France): World War I: The fishing vessel was sunk in the Atlantic Ocean 10 nmi north west of Pendeen, Cornwall (50.25°N, -5.88333°W) by SMU UC-48.
 * SS Rockingham (1902) (🇺🇸 United States): World War I: The cargo ship was sunk in the Atlantic Ocean 150 nmi west north west of Ireland (55.2°N, -12.5°W) by SMU U-69 with the loss of two of her crew.
 * SS San Urbano (1913) ( undefined): World War I: The tanker was torpedoed and sunk in the Atlantic Ocean 180 nmi north west by north of the Fastnet Rock (51.55°N, -13.63333°W) by SMU U-81 with the loss of four of her crew.
 * SMU U-81 : World War I: The Type U 81 submarine was torpedoed and sunk in the Atlantic Ocean west of Ireland (51.55°N, -13.63333°W) by HMS E54 with the loss of 24 of her crew.
 *  W. D. Potts ( undefined): World War I: The schooner was shelled and sunk in the Irish Sea 10 nmi south west of Portpatrick by SMU UC-65 . Her crew survived.

2 May

 * SS Alessandria (1911) ( undefined): World War I: The cargo ship was sunk in the Mediterranean Sea 100 nmi north of Benghazi, Libya by SMU UC-74.
 * SS Amber (1892) ( undefined): World War I: The coaster was scuttled in the Irish Sea 2 nmi Ballyherbert, County Down by SMU UC-65 . Her crew survived.
 *  Beeswing ( undefined): World War I: The barque was shelled and sunk in the Atlantic Ocean 140 nmi west by north of the Fastnet Rock  (50.83333°N, -13°W) by SMU U-58 . Her crew survived.
 * SS Camerata (1910) ( undefined): World War I: The cargo ship was torpedoed and damaged in the Mediterranean Sea off Djidjelli, Algeria by SMU UC-37 . She was beached but was later refloated.
 *  Cancalais (🇫🇷 France): World War I: The three-masted schooner was torpedoed and sunk in the Bay of Biscay 12 nmi north west of the Île d'Yeu, Vendée (46.91667°N, -2.38333°W) by SMU UC-72 . Her crew survived.
 * SS Certo (1910) (🇳🇴 Norway): World War I: The cargo ship struck a mine and sank in the English Channel off Le Havre, Seine-Maritime, France. Her crew survived.
 * SS Derrymore (1905) ( undefined): World War I: The coaster was scuttled in the Irish Sea off Ballyherbert by SMU UC-65 . Her crew survived.
 * HMS Derwent (1903) : World War I: The River-class destroyer struck a mine and sank in the English Channel off Le Havre (49.51667°N, -0.03333°W) with the loss of 58 of her 70 crew.
 * Dione (🇳🇴 Norway): World War I: The sailing vessel was sunk in the Atlantic Ocean south west of Ireland (50.65°N, -11.75°W) by SMU U-58 . Her crew survived.
 *  Earnest ( undefined): World War I: The schooner was scuttled in the Irish Sea 6 nmi south east by south of the Skulmartin Lightship ( undefined) by SMU UC-65 . Her crew survived.
 * SS Gena (1893) ( undefined): World War I: The cargo ship was torpedoed and sunk in the North Sea off Aldeburgh, Suffolk by an Imperial German Air Corps aircraft. Her crew survived.
 * SS Juno (1882) ( undefined): World War I: The cargo ship was sunk in the English Channel 17 nmi east of the Barfleur Lighthouse, Manche, France (49.8°N, -0.85°W) by SMU UB-18 with the loss of a crew member.
 * FRENCH TRAWLER Keryado : World War I: The naval trawler was torpedoed and sunk in the Bay of Biscay 12 nmi north west of the Île d'Yeu (46.76667°N, -2.68333°W) by SMU UC-72 with the loss of sixteen of her crew.
 * SS Morion (1894) ( undefined): World War I: The coaster was scuttled in the Irish Sea 4 nmi south east of the Skulmartin Lightship ( undefined) by SMU UC-65 . Her crew survived.
 *  Natuna (🇳🇴 Norway): World War I: The barque was sunk in the Atlantic Ocean 70 nmi west of the Shetland Islands, United Kingdom (59.83333°N, -3.16667°W) by SMU U-44 . Her crew survived.
 *  Nordzee (🇳🇱 Netherlands): World War I: The koff was scuttled in the North Sea off the Noord Hinder Lightship (🇳🇱 Netherlands) by SMU UC-62 . Her crew survived.
 * SS Rikard Noordrak (1901) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 9 nmi south of Whitby, Yorkshire (54.38333°N, -0.36667°W) by SMU UB-21 with the loss of two of her crew.
 *  Russie (🇫🇷 France): World War I: The schooner was scuttled in the Bay of Biscay 12 nmi north west of the Île d'Yeu (46.76667°N, -2.68333°W) by SMU UC-72 . Her crew survived.
 * SS Saint Mungo (1907) ( undefined): World War I: The coaster was scuttled in the Irish Sea 2 nmi north north east of the South Rock Lightship ( undefined) by SMU UC-65.
 * SS Taizan Maru (1895) (🇯🇵 Japan): World War I: The cargo ship was sunk in the Irish Sea 11 nmi west of the Mull of Galloway (54.46667°N, -5.33333°W) by SMU UC-65 . Her crew survived.
 * SS Tela (1917) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 16 nmi north east of Cape Barfleur, Manche (49.83333°N, -0.83333°W) by SMU UB-18 . Her crew survived.
 * SS Troilus (1917) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 140 nmi west north west of Malin Head, County Donegal (53.36667°N, -15.86667°W) by SMU U-69 . Her crew survived.
 * United ( undefined): World War I: The fishing smack was scuttled in the Atlantic Ocean 5 nmi off the Godrevy Lighthouse, Cornwall (50.21667°N, -5.88333°W) by SMU UC-48 . Her crew survived.
 *  Vanduara (🇳🇴 Norway): World War I: The barque was shelled and sunk in the Atlantic Ocean south west of Ireland (50.4°N, -14.98333°W) by SMU U-58 . Her crew survived.
 *  Victoire (🇫🇷 France): World War I: The schooner was scuttled in the Bay of Biscay (46.76667°N, -2.68333°W) by SMU UC-72 . Her crew survived.
 * SS Warnow (1883) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 6 nmi west of Trevose Head, Cornwall (50.5°N, -5.16667°W) by SMU UC-48 with the loss of fourteen of her crew.
 * Westland (🇳🇱 Netherlands): World War I: The fishing vessel was scuttled in the North Sea off the Terschelling Lightship (🇳🇱 Netherlands) (53.78333°N, 4.35°W) by SMU UC-71 . Her crew survived.
 * Yvonne (🇫🇷 France): World War I: The sailing vessel was sunk in the Bay of Biscay 12 nmi north west of the Île d'Yeu (46.76667°N, -2.68333°W) by SMU UC-72 . Her crew survived.

3 May

 * SS Antonio Sciesa (1887) ( undefined): World War I: The cargo ship was sunk in the Ionian Sea 24 nmi south south east of Sapientza, Greece (36.65°N, 21.25°W) by SMU U-14 (Austria-Hungary) . Her crew survived.
 * Carberry King ( undefined): World War I: The drifter was scuttled in the English Channel 14 nmi south of The Lizard, Cornwall (49.73333°N, -5.11667°W) by SMU UC-75 . Her crew survived.
 * SS Clodmoor (1902) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 5 nmi south west of Newhaven, East Sussex (50.71667°N, -0.01667°W) by SMU UB-40 . Her crew survived.
 * Eleanor ( undefined): World War I: The fishing vessel was scuttled in the English Channel (49.75°N, -5.11667°W) by SMU UC-75.
 * Fastnet ( undefined): World War I: The fishing vessel was scuttled in the English Channel (49.75°N, -5.11667°W) by SMU UC-75.
 * Fils du Progres (🇫🇷 France): World War I: The trawler was sunk in the Atlantic Ocean 3 nmi south west of the Île de Sein, Finistère by SMU UC-61 . Her crew survived.
 * SS Frederick Knight (1898) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 115 nmi north west by west of the Fastnet Rock (51.71667°N, -12.35°W) by SMU U-62 . Her crew survived.
 * SS Giovannina (1892) ( undefined): World War I: The cargo ship was sunk in the Bay of Biscay 10 nmi south west of Belle Île, Morbihan, France by SMU UC-61.
 * SS Glen Tanar (1909) ( undefined): World War I: The coaster struck a mine and sank in the North Sea 1 nmi north east of Girdle Ness, Aberdeenshire (57.16667°N, -2.03333°W). Her crew survived.
 *  Helge (🇩🇰 Denmark): World War I: The schooner was scuttled in the North Sea (56.46667°N, 3.71667°W) by SMU UC-49 . Her crew survived.
 * Hibernia ( undefined): World War I: The fishing vessel was sunk in the Atlantic Ocean 14 nmi south east of Baltimore, County Cork by SMU UC-75.
 *  Lindisfarne ( undefined): World War I: The full-rigged ship was scuttled in the Atlantic Ocean south west of Ireland (40.33333°N, -14°W) by SMU U-21 (Germany).
 * Lucky Lass ( undefined): The fishing vessel was scuttled in the English Channel (49.56667°N, -5.11667°W) by SMU UC-75.
 * SS Maria (1898) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Bay of Biscay by SMU UC-69 . Her crew survived.
 *  Mezly (🇫🇷 France): World War I: The barque was shelled and sunk in the Atlantic Ocean (50.25°N, -15.6°W) by SMU UC-73 . Her crew survived.
 * SS Misurata (1888) ( undefined): World War I: The cargo ship was shelled and sunk in the Atlantic Ocean 50.16667°N, -17.25°W) by SMU UC-73 . Her crew survived.
 * North Star ( undefined): World War I: The fishing vessel was scuttled in the English Channel (49.75°N, -5.08333°W) by SMU UC-75.
 * SS Polstad (1907) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean off Cape Ortegal, Spain (43.71667°N, -7.1°W) by SMU UC-69 . Her crew survived.
 * Sir Edward Birkbeck ( undefined): World War I: The fishing vessel was scuttled in the English Channel by SMU UC-75 . Her crew survived.
 * SS Truvor (1889) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Barents Sea off Mys Zyp-Navolok (70.13333°N, 33.11667°W) by SMU U-45 . Her crew survived.
 * SS Ussa (1913) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 2.5 nmi off Cherbourg, Seine-Maritime, France by SMU UC-26 . Her crew survived.
 * SS Washington (1907) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Gulf of Genoa 1.5 nmi off Camogli, Liguria, Italy (44.23333°N, 9.11667°W) by SMU U-63 (Germany) . Her crew survived.

4 May

 * SS Aghios Nikolaos (1887) (🇬🇷 Greece): World War I: The cargo ship was sunk in the English Channel 16 nmi south east of Barfleur, Manche, France (49.71667°N, -0.9°W) by SMU UB-38 . Her crew survived.
 * SS Assos (🇬🇷 Greece): World War I: The cargo ship was captured and scuttled in the English Channel 16 nmi south east of Barfleur 49.71667°N, -0.9°W by SMU UB-38.
 * FRENCH WHALER Caméléon : World War I: The naval whaler struck a mine and sank in the Gulf of Patras off Cape Papas, Greece with the loss of a crew member.
 *  Francesco C. ( undefined): World War I: the barque was scuttled in the Mediterranean Sea west of Sardinia (40.3°N, 8.13333°W) by SMU U-34 (Germany).
 * SS Herrington (1905) ( undefined): World War I: The collier struck a mine and sank in the North Sea 0.75 nmi east south east of Red Head, Forfarshire (56.61667°N, -2.45°W). Her crew survived.
 * SS Ilva (1893) ( undefined): World War I: The cargo ship was captured and scuttled in the Bay of Biscay 5 nmi off Coelleira Island, Galicia, Spain by SMU UC-69 . Her crew survived.
 * SS Ioannis p. Goulandris (1897) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Bay of Biscay 23 nmi east of the Punta de Estaca de Bares by SMU UC-69 . Her crew survived.
 *  Jørgen Olsen (🇩🇰 Denmark): World War I: The three-masted schooner was shelled and damaged in the Atlantic Ocean 30 nmi west of Ireland by SMU U-62 . Her crew survived but she was declared a constructive total loss.
 *  Joseph ( undefined): World War I: The brigantine was scuttled in the English Channel 20 nmi north of Caen, Calvados, France (49.65°N, -0.63333°W) by SMU UB-38 . Her crew survived.
 * HMT Lord Salisbury : The naval trawler was lost on this date.
 * SS Marie (1910) (🇩🇰 Denmark): World War I: The coaster was torpedoed and sunk in the North Sea off Aberdeen, United Kingdom (58.5°N, -1.06667°W) by SMU UC-51 with the loss of two of her crew.
 * Marie (🇫🇷 France): World War I: The sailing vessel was sunk in the Atlantic Ocean south of Ireland by SMU UC-75.
 * Mamelena IX (🇪🇸 Spain): World War I: The trawler was scuttled in the Bay of Biscay south west of the Contis Lighthouse, Landes, France by SMU UC-72
 * Mamelena XII (🇪🇸 Spain): World War I: The trawler was scuttled in the Bay of Biscay south west of the Contis Lighthouse by SMU UC-72.
 * FRENCH TRAWLER Marne : World War I: The naval trawler was shelled and sunk in the Bay of Biscay south west of the Contis Lighthouse by SMU UC-72 . Her crew survived.
 * SS Neptunus (1916) (🇳🇱 Netherlands): World War I: The coaster was scuttled in the North Sea 10 nmi north of the North Hinder Lightship (🇳🇱 Netherlands) by SMU UC-62.
 *  New Design No.2 ( undefined): World War I: The schooner was scuttled in the Irish Sea 25 nmi north by west of the South Bishop Lighthouse by SMU UC-65 . Her crew survived.
 * SS Pilar de Larrinaga (1902) ( undefined): World War I: The cargo ship was torpedeoed and sunk in the Atlantic Ocean 2 nmi south east by south of the Tuskar Rock, Ireland (52.16667°N, -6.13333°W) by SMU UC-65 with the loss of twenty of her crew.
 * SS Sagamore ( undefined): World War I: The cargo ship was torpedoed and sunk in Atlantic Ocean the off the coast of Portugal by SMU UC-69 . Her crew survived.
 * Sophie (🇩🇰 Denmark): World War I: The sailing vessel was sunk in the North Sea by SMU UC-42.
 * Strumble ( undefined): World War I: The fishing smack was scuttled in the Irish Sea 10 nmi north north east of Strumble Head, Pembrokeshire by SMU UC-65 . Her crew survived.
 * SS Transylvania (1914) ( undefined): World War I: The troopship was torpedoed and sunk in the Gulf of Genoa 2.5 nmi off Cape Vado, Liguria, Italy (44.25°N, 8.5°W) by SMU U-63 with the loss of 402 lives.
 * SS Tromp (1898) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean 2 nmi off Rencardeida Point, Spain (43.76667°N, -7.56667°W) by SMU UC-69 . Her crew survived.
 * SS Vale (1913) (🇳🇴 Norway): World War I: The coaster was torpedoed and sunk in the North Sea 68 nmi east by north of the Isle of May, Fife, United Kingdom (56.03333°N, -1°W) by SMU UC-77 with the loss of three of her crew.
 * Verdun (🇫🇷 France): World War I: The fishing vessel was shelled and sunk in the Bay of Biscay south west of the Contis Lighthouse by SMU UC-72 . Her crew survived.
 * Victorious ( undefined): World War I: The fishing vessel was scuttled in the Irish Sea 10 nmi north north east of Strumble Head by SMU UC-65 . Her crew survived.

5 May

 *  Angela ( undefined): World War I: The schooner struck a mine and sank in the North Sea 3 nmi off the mouth of the River Tyne (54.98333°N, -1.31667°W) with the loss of five of her crew.
 *  Asra (🇳🇴 Norway): World War I: The full-rigged ship was shelled and sunk in the Atlantic Ocean 140 nmi west north west of Tory Island, County Donegal, United Kingdom (55.66667°N, -12.16667°W) by SMU U-58 . Her crew survived.
 * Dina di Lozenzo ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea north of Bizerte, Algeria by SMU UC-37.
 * Edith Cavell ( undefined): The trawler was scuttled in the North Sea off Robin Hood's Bay, Yorkshire by SMU UB-21.
 * SS Feltria (1891) ( undefined): World War I: The passenger ship was torpedoed and sunk in the Atlantic Ocean 8 nmi south east of Mine Head, County Cork (51.93333°N, -7.4°W) by SMU UC-48 with the loss of 45 lives.
 * SS Greta (1903) ( undefined): World War I: The coaster was shelled and sunk in the Atlantic Ocean 11 nmi south east of Mine Head, County Cork by SMU UC-48 . Her crew survived.
 * SS Harmattan (1911) ( undefined): World War I: The cargo ship struck a mine and sank in the Mediterranean Sea 30 nmi off Cape Bon, Algeria with the loss of 36 of her crew.
 * HMS Lavender (1915) : World War I: The Acacia-class sloop was sunk in the English Channel south of Mine Head, Cornwall by SMU UC-75 with the loss of 22 of her 77 crew.
 * SS Lodes (1898) ( undefined): World War I: The coaster struck a mine and sank in the Irish Sea 4 nmi south east of Ballycotton, County Cork with the loss of seven of her crew.
 * SS Nydal (1916) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Bay of Biscay 25 nmi west south west of the La Coubre Lighthouse, Charente-Maritime, France by SMU UC-72 . Her crew survived.
 * SS Odense (1890) (🇩🇰 Denmark): World War I: The cargo ship was damaged in the North Sea 1.5 nmi east north east of St Abb's Head, Berwickshire, United Kingdom (55.93333°N, -2.2°W) by SMU UC-77 and was abandoned with the loss of two of her crew. Odense came ashore north of St Abb's Head and was declared a total loss. She sank on 2 August.
 * SS Segovia (1903) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 26 nmi south south east of Auskerry, Orkney Islands, United Kingdom (58.63333°N, -2°W) by SMU UC-51 . Her crew survived.
 * Simon (🇳🇱 Netherlands): World War I: The fishing vessel was shelled and sunk in the North Sea off the Terschelling Lightship (🇳🇱 Netherlands) (53.51667°N, 3.66667°W) by SMU UC-71 with the loss of all eleven crew.
 *  Snig (🇳🇴 Norway): World War I: The barque was sunk in the Atlantic Ocean 200 nmi west of Tory Island (54.13333°N, -13.6°W) by SMU U-49 . Her crew survived.

6 May

 * SS Adansi (1901) ( undefined): World War I: The Elder Dempster 2,644 grt cargo ship was torpedoed and sunk in the Atlantic Ocean 80 nmi west of the Fastnet Rock (50.66667°N, -11.08333°W) by SMU U-21 (Germany) while en route from Sierra Leone to Liverpool. Her crew survived.
 * SS Francesco (1896) ( undefined): World War I: The cargo ship was sunk in the Bay of Biscay off the La Coubre Lighthouse, Charente-Maritime, France by SMU UC-72 . Her crew survived.
 * SS Gurth (1910) (🇳🇴 Norway): World War I: The cargo ship was scuttled in the Bay of Biscay 1.5 nmi off Vaca de Luanco, Spain (43.65°N, -5.8°W) by SMU UC-69 . Her crew survived.
 * SS Harold (1878) (🇸🇪 Sweden): World War I: The cargo ship was shelled and sunk in the North Sea 76 nmi north east by north of the mouth of the River Tyne by SMU UB-21 with the loss of five crew.
 * SS Hebble (1891) ( undefined): World War I: The coaster struck a mine and sank in the North Sea 1.5 nmi east of Roker, County Durham (54.91667°N, 1.3°W) with the loss of five of her crew.
 * SS Kaparika (1894) (🇳🇴 Norway): World War I: cargo ship was torpedoed and sunk in the North Sea 30 nmi east of Aberdeen, United Kingdom by SMU UC-77 with the loss of a crew member.
 * Poseidon I (🇳🇱 Netherlands): World War I: The fishing vessel was shelled and sunk in the North Sea 9 nmi north of the Dogger Bank North Lightship ( undefined) by SMU UC-30 . Her crew survived.
 *  President (🇫🇷 France): World War I: The barque was shelled and sunk in the Atlantic Ocean 12 nmi west of Trevose Head, Cornwall, United Kingdom (50.51667°N, -5.35°W) by SMU UC-75 . Her crew survived.
 * SS Voss (1895) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Bay of Biscay 1.5 nmi off Vaca de Luanco (43.65°N, -5.78333°W) by SMU UC-69 . Her crew survived.

7 May

 * SS Crown of Leon (1894) ( undefined): World War I: The cargo ship was torpedoed and damaged in the Gulf of Genoa (44.13333°N, 8.23333°W) by SMU U-63 (Germany) with the loss of a crew member. She was beached but was torpedoed again on 16 May by SMU U-32 (Germany).
 *  H. H. Petersen (🇩🇰 Denmark): World War I: The barquentine was sunk in the Atlantic Ocean 20 to 25 nmi west of St. Kilda, Inverness-shire, United Kingdom (57.5°N, -9°W) by SMU U-80 . Her crew survived.
 * SS Kinross (1911) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 10 nmi east of the Wolf Rock, Cornwall (49.81667°N, -5.55°W) by SMU UC-48 . Her crew survived.
 * SS Leikanger (1916) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean 5 nmi west nort west of the Machico Lighthouse, Madeira, Portugal by SMU UC-69 . Her crew survived.
 * SS Lowmount (1888) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 4 nmi off the Nab Lightship ( undefined) with the loss of five of her crew.
 * Martha Maria (🇳🇱 Netherlands): World War I: The trawler was sunk in the North Sea (52.83333°N, 4.13333°W) by SMU UB-20 . Her crew survived.
 *  Maude ( undefined): World War I: The schooner was scuttled in the Irish Sea 8 nmi south west of Bardsey Island, Pembrokeshire by SMU UC-65 . Her crew survived.
 * SS Polamhall (1901) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 80 nmi west south west of the Bishop Rock, Isles of Scilly (49.03333°N, -8.06667°W) by SMU U-62 . Her crew survived.
 * Prins Hendrik de Nederlande (🇳🇱 Netherlands): World War I: The trawler was sunk in the North Sea (52.83333°N, 4.16667°W) by SMU UB-20 . Her crew survived.
 * SS Repton (1894) ( undefined): World War I: The collier was torpedoed and sunk in the Mediterranean Sea 45 nmi south south east of Cape Matapan, Greece (35.7°N, 22.95°W) by SMU UB-43 with the loss of three of her crew.
 *  Sophie (🇩🇰 Denmark): World War I: The schooner was sunk in the Atlantic Ocean 30 nmi east south oeast of St. Kilda (57.66667°N, -9.08333°W) by SMU U-80 . Her crew survived.
 * SS Tiger (1895) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean 3 nmi west north west of Cabo Machico, Madeira (43.45°N, -2.83333°W) by SMU UC-69 . Her crew survived.
 * SS Tore Jarl (1903) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 95 nmi south of Sumburgh Head, Shetland Islands, United Kingdom by SMU UC-49 with the loss of a crew member.
 * SMU UB-39 : World War I: The Type UB II submarine struck a mine and sank in the North Sea (51.33333°N, 2.15°W) with the loss of all 24 crew.
 * HMY Zarefah : World War I: The naval yacht struck a mine and sank in the North Sea 1 nmi north east of Mull Head, Mainland, Orkney Islands with the loss of sixteen of her crew.

8 May

 * Iris ( undefined): World War I: The ketch was sunk in the English Channel off Cherbourg, Seine-Maritime, France, probably by SMU UC-26, with the loss of four of her crew.
 *  Killarney ( undefined): World War I: The barque was shelled and sunk in the Atlantic Ocean 200 nmi west of the Fastnet Rock (50.91667°N, -14.73333°W) by SMU U-21 (Germany) . Her crew survived.
 * SS Nelly (1883) (🇫🇷 France): World War I: The cargo ship was sunk in the Bay of Biscay 44 nmi south south west of Penmarc'h, Finistère (47.3°N, -4.91667°W by SMU UC-61 with the loss of a crew member.
 * SS Petunia (1889) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 45 nmi west of the Bishop Rock, Isles of Scilly by SMU U-49 with the loss of two crew. Three survivors were taken as prisoners of war.
 * SMU UC-26 : World War I: The Type UC II submarine was rammed and sunk in the English Channel off Calais, Pas-de-Calais, France (51.05°N, 1.66667°W) by HMS Milne (1914) with the loss of all 26 crew.

9 May

 * Dio ti Guardi ( undefined): World War I: The fishing vessel was sunk in the Mediterranean Sea off Cape Rosello, Sicily by SMU UC-35.
 * SS Hans Broge (1907) (🇩🇰 Denmark: World War I: The cargo ship was sunk in the Atlantic Ocean 30 nmi west of Teelin Head, County Donegal, United Kingdom (54.63333°N, -9.5°W) by SMU U-80 . Her crew survived.
 * SS Harpagus (1910) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 62 nmi south west of the Île du Planier, Bouches-du-Rhône, France (42.53333°N, 4.65°W) by SMU U-34 (Germany) with the loss of three crew. Two crew were taken as prisoners of war.
 * Kitty ( undefined): World War I: The fishing vessel was scuttled in the North Sea 30 nmi east south east of St Abb's Head, Berwickshire (56.18333°N, -1.75°W) by SMU UC-42 . Her crew survived, but two of them were taken as prisoners of war.
 * L'Oriente ( undefined): World War I: The fishing vessel was scuttled in the Mediterranean Sea off Cape Rosello by SMU UC-35.
 *  Marchiena (🇳🇱 Netherlands): World War I: The schooner was shelled and sunk in the English Channel off Beachy Head, East Sussex, United Kingdom by SMU UC-17 . Her crew took to the lifeboats but were not rescued.
 * Peppino Aiello ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Cape Rosello by SMU UC-35.
 * San Pietro ( undefined): World War I: The fishing vessel was sunk in the Mediterranean Sea off Cape Rosello by SMU UC-35.
 * Windward Ho! ( undefined): World War I: The trawler struck a mine and sank in the North Sea 3 nmi south of Peterhead, Aberdeenshire (57.46667°N, -1.7°W) with the loss of eight of her crew.

10 May

 *  Berangère (🇫🇷 France): World War I: The full-rigged ship was shelled and sunk in the Atlantic Ocean south west of Ireland (50.1°N, -11.5°W) by SMU U-62 . All 22 crew survived.
 * SS Broomhill (1909) ( undefined): World War I: The collier was scuttled in the English Channel 9 nmi south west of Portland Bill, Dorset (50.41667°N, -2.53333°W) by SMU UC-61 with the loss of two of her crew.
 *  Carmen (🇪🇸 Spain): World War I: The three-masted schooner was scuttled in the Mediterranean Sea 12 nmi south of Barcelona by SMU U-34 (Germany).
 * SS Dolcoath (1882) ( undefined): World War I: The cargo ship struck a mine and sank in the North Sea 3.25 nmi north east of North Foreland, Kent (51.43333°N, 1.46667°W) with the loss of a crew member.
 * Gazelle (🇳🇴 Norway): World War I: The sailing ship was scuttled in the Atlantic Ocean 80 nmi south west of the Fastnet Rock (49.75°N, -10.83333°W) by SMU U-62 . Her crew survived.
 * Gruno (🇳🇱 Netherlands): World War I: The auxiliary sailing vessel was sunk in the North Sea 8 nmi south south west of the Noord Hinder Lightship (🇳🇱 Netherlands) by SMU UC-63.
 * Leone XIII ( undefined): The sailing vessel was sunk in the Mediterranean Sea off Marettimo by SMU UC-35.
 * HMT Lord Ridley : World War I: The naval trawler struck a mine and sank in the North Sea off Whitby, Yorkshire (54.51667°N, -0.61667°W) with the loss of ten of her crew.
 * SS Minerva (1864) (🇳🇴 Norway): World War I: The coaster was sunk in the English Channel 15 nmi west of Portland Bill by SMU UC-61 . Her crew survived.
 * SS Sebastian ( undefined): The tanker caught fire in the Atlantic Ocean. She was taken in tow by a United States Navy gunboat but subsequently sank.
 * SS Veni (1901) (🇳🇴 Norway): World War I: The coaster was sunk in the English Channel 15 nmi west of Portland Bill (50.53333°N, -2.78333°W) by SMU UC-17 . Her crew survived.

11 May

 *  Anna Alwina ( undefined): World War I: The brigantine was sunk in the Atlantic Ocean south west of Ireland by SMU U-80.
 * SS Barrister (1915) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 7 nmi south of Mine Head, County Waterford by SMU U-49 . Her crew survived.
 * HMT Bracklyn : World War I: The naval trawler struck a mine and sank in the North Sea off Great Yarmouth, Norfolk (52.7°N, 2.16667°W) with the loss of ten of her crew.
 * SS Calchas (1899) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 3 nmi west by south of Tearaght Island, County Donegal (52°N, -10.66667°W) by SMU U-80 . Her crew survived.
 * SS Hermes (1897) ( undefined): World War I: The cargo ship was shelled and sunk in the Barents Sea off Vardø, Finnmark, Norway (71.26667°N, 33.75°W) by SMU U-45 with the loss of all 34 crew.
 * SS Hindoo (1905) ( undefined): World War I: The cargo ship was torpedoed and damaged in the Mediterranean Sea between Algiers and Ténès, Algeria (36.61667°N, 1.91667°W) by SMU U-47 (Germany) and was beached. She was later refloated.
 * SS Italia (1891) ( undefined): The cargo ship ran aground and sank on the Wingletang Rock, Isles of Scilly, United Kingdom.
 * SS Lady Charlotte (1905) ( undefined): The collier ran aground and sank at Porth Hellick Point, Isles of Scilly. Her crew survived.
 * SS Lefkosia (1872) (🇬🇷 Greece): World War I: The cargo ship was scuttled in the Mediterranean Sea off Cape Tortosa, Spain (40.81667°N, 1°W) by SMU U-34 (Germany) . Her crew survived.
 * Limassol ( undefined): World War I: The sailing vessel was scuttled in the Tyrrhenian Sea off Montecristo, Italy by SMU UC-35.
 * Luisa Madre ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea off Cape Figari, Sardinia by SMU UC-35.
 * Maddelena Madre ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea off Cape Figari by SMU UC-35.
 * SS Medjerda (1898) (🇫🇷 France): World War I: The troopship was torpedoed and sunk in the Mediterranean Sea6 nmi off Cape Tortosa (40.75°N, 1.2°W) by SMU U-34 (Germany) with the loss of 344 lives.
 * Rosalia Madre ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea off Cape Figari by SMU UC-35.
 * San Antonio ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea off Cape Figari by SMU UC-35.
 * SS Tarpeia (1905) ( undefined): World War I: The coaster was scuttled in the English Channel 9 nmi north of Port-en-Bessin, Manche, France (49.5°N, -0.81667°W) by SMU UB-18 . Her crew survived.

12 May

 * SS Egyptian Prince (1902) ( undefined): World War I: The cargo ship was scuttled in the Mediterranean Sea 240 nmi south south east of Malta (34.33333°N, 18.86667°W) by SMU U-38 . Her crew survived.
 * SS Galicia (1901) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 3 nmi east of Teignmouth, Devon (50.53333°N, -3.4°W). Her crew survived.
 * G.L.C. ( undefined): World War I: The fishing smack was scuttled in the Atlantic Ocean south east of the Eddystone Lighthouse by SMU UC-17 . Her crew survived.
 * SS Locksley Hall (1893) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 30 nmi south east by south of Malta 35.38333°N, 14.93333°W) by SMU U-32 (Germany) with the loss of six crew.
 * SS Refugio (1905) ( undefined): World War I: The cargo ship was shelled and sunk in the Atlantic Ocean 115 nmi north west of Tory Island, County Donegal (55.16667°N, -11.58333°W) by SMU U-57 with the loss of a crew member.
 * SS San Onofre (1914) ( undefined): World War I: The tanker was torpedoed and sunk in the Atlantic Ocean 64 nmi north west of the Skelligs (52.41667°N, -11.7°W) by SMU U-48 with the loss of a crew member.
 * SS Waterville (1891) ( undefined): World War I: The cargo ship struck a mine and was damaged in the North Sea. She was beached but was later refloated. Her crew survived.
 * SS Wirral (1911) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Norwegian Sea 23 nmi north west of Utvær, Sogn og Fjordane, Norway by SMU U-19 (Germany) with the loss of a crew member.
 * SS Zanoni (1907) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 12 nmi north east by east of Cape Oropesa, Spain (40.16667°N, 0.41667°W) by SMU U-34 (Germany) with the loss of a crew member.

13 May

 *  Anna (🇩🇰 Denmark): World War I: The three-masted barque was sunk in the English Channel 30 nmi north east of the Île de Batz, Finistère, France (49.2°N, -4.43333°W) by SMU UC-17 . Her crew survived.
 *  Hudson (🇳🇴 Norway): World War I: The barque was sunk in the Atlantic Ocean 30 nmi north north west of Ouessant, Finistère (48.8°N, -7.93333°W) by SMU UC-17 . Her crew survived.
 * SS Jessmore (1911) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 180 nmi west north west of the Fastnet Rock by SMU U-48 . Her crew survived.
 * L'Independiente F ( undefined): World War I: The sailing vessel was scuttled in the Mediterranean Sea south of the Cabo de Gata, Spain (36.51667°N, -2.03333°W) by SMU U-47 (Germany).
 * SS Rio Amazonas (1891) ( undefined): World War I: The cargo ship was sunk in the Mediterranean Sea 150 nmi south west of Crete, Greece (33.66667°N, 20.76667°W) by SMU U-38 . Her crew survived.

14 May

 * Bel Lily ( undefined): World War I: The trawler struck a mine and sank in the North Sea 1.5 nmi east north east of Peterhead, Aberdeenshire with the loss of ten of her crew.
 *  Cairnmoney ( undefined): World War I: The barque was scuttled in the Atlantic Ocean 150 nmi west of the Fastnet Rock by SMU U-49 . Her crew survived.
 *  Elizabeth Hampton ( undefined): World War I: The schooner was scuttled in the English Channel 25 nmi south by west of St. Catherine's Point, Isle of Wight by SMU UB-18 . Her crew survived.
 * SS Farley (1916) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 70 nmi south west of the Bishop Rock, Isles of Scilly (48.93333°N, -7.36667°W) by SMU UC-17 . Her crew survived.
 *  Francesco Raiola ( undefined): World War I: The brigantine was scuttled in the Mediterranean Sea east of Sicily (37.68333°N, 15.48333°W) by SMU U-63 (Germany).
 * Gravelinoise (🇫🇷 France): World War I: The sailing vessel was scuttled in the Mediterranean Sea 12 nmi east of Valencia, Spain (39.45°N, -0.08333°W) by SMU U-34 (Germany) . Her crew survived.
 * SS Tamon Maru No.11 (1889) (🇯🇵 Japan): The cargo ship sank at Aburatsu, Hyūga, Miyazaki.
 * Tejo (🇵🇹 Portugal): World War I: The sailing vessel was scuttled in the Mediterranean Sea (38.96667°N, 0.3°W) by SMU U-34 (Germany) . Her crew survived.
 * SMU U-59 : World War I: The Type U 57 submarine struck a mine and sank in the North Sea (55.55°N, 7.25°W) with the loss of 33 of her 37 crew.
 * SS Volga (1903) ( undefined): World War I: The cargo ship was torpedoed and damaged in the Mediterranean Sea east of Sicily by SMU U-63 (Germany) . She was beached but was later refloated.

15 May

 * HMT Admirable : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * HMT Avondale : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * ITALIAN DESTROYER Borea : World War I: The Nambo-class destroyer was shelled and sunk in the Adriatic Sea off the coast of Albania by AUSTRO-HUNGARIAN DESTROYER Balaton and AUSTRO-HUNGARIAN DESTROYER Csepl (both ).
 * Boreas (🇳🇱 Netherlands): World War I: The auxiliary sailing vessel was sunk in the North Sea 25 nmi north west of IJmuiden, North Holland by SMU UC-71.
 * FRENCH DESTROYER Boutefeu : World War I: Battle of the Strait of Otranto: The Bouclier-class destroyer struck a mine and sank in the Strait of Otranto off Brindisi, Apulia, Italy.
 * HMT Coral Haven : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * HMT Craignoon : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 *  Cuba ( undefined): World War I: The barquentine was scuttled in the English Channel 10 nmi west of the Owers Lightship ( undefined) by SMU UB-40 . Her crew survived.
 * HMT Felicitas : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * SS Ferrara (1912) ( undefined): World War I: The cargo ship was torpedoed and damaged in the Strait of Messina by SMU U-63 (Germany) . She was beache but was later refloated.
 * HMT Girl Gracie : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * HMT Girl Rose : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * SS Grosholm (1914) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean 200 nmi west of Ireland (55.88333°N, -12.25°W) by SMU U-46 . Her crew survived.
 * HMT Helenora : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * SS Meuse (1914) (🇫🇷 France): World War I: The cargo ship was sunk in the Atlantic Ocean west of the Fastnet Rock (50.81667°N, -15.45°W) by SMU U-48.
 * SS Pancras (1911) ( undefined): World War I: The cargo ship was shelled and damaged in the Mediterranean Sea off Punta Sabinal, Spain by SMU U-47 (Germany) and was beached. She was later refloated.
 * SS Panaghi Lykiardopoulo (1900) (🇬🇷 Greece): World War I: The cargo ship was sunk in the English Channel west of the Roches-Douvres Lighthouse (49°N, -3.53333°W) by SMU UB-18 . Her crew survived.
 * SS Polymnia (1903) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 15 nmi west of The Lizard, Cornwall by SMU UC-75 with the loss of eight of her crew.
 * HMT Quarry Knowe : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 *  Rosina ( undefined): The brigantine ran aground at Ribeirinha Point, Faial, Azores, Portugal and was a total loss. Her crew were rescued.
 * ITALIAN TORPEDO BOAT Scorpione : The Sirio-class torpedo boat collided with FRENCH GUNBOAT Surveillante and sank in the Mediterranean Sea off Pantellaria.
 * HMT Selby : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * HMT Serene : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * SS St. Frances (🇺🇸 United States): The cargo ship ran aground at Unimak Pass, Alaska and was a total loss.
 * HMT Taits : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * HMT Transit : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.
 * SS Tung Shan (1899) ( undefined): World War I: The cargo ship was scuttled in the Mediterranean Sea 7 nmi north of Cape San Antonio, Spain (39.03333°N, 0.31667°W) by SMU U-34 (Germany)  with the loss of a crew member. Three crew were taken as prisoners of war.
 * HMT Young Linnet : World War I: Battle of the Strait of Otranto: The naval trawler was sunk in the Adriatic Sea by an Austro-Hungarian navy warship.

16 May

 * HMS Dartmouth (1911) : World War I: Battle of the Strait of Otranto: The Town-class cruiser was torpedoed and totally disabled in the Strait of Otranto off Brindisi, Apulia, Italy by SMU UC-25 with the loss of five of her 433 crew. She was later repaired and returned to service.
 *  Dorothy Duff ( undefined): World War I: The schooner was scuttled in the Mediterranean Sea 14 nmi off Cape Cullera, Spain (39.26667°N, 0.13333°W) by SMU U-34 (Germany) . Her crew survived.
 *  Friso (🇳🇱 Netherlands): World War I: The schooner was sunk in the English Channel south east of Start Point, Devon, United Kingdom by SMU UB-20.
 * Hendrika Johana (🇳🇱 Netherlands): World War I: The sailing vessel was shelled and sunk in the North Sea north of the Maas Lightship (🇳🇱 Netherlands) (52.51667°N, 4.33333°W) by SMU UC-71.
 * SS Highland Corrie (1910) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 4 nmi south of the Owers Lightship ( undefined) (50.46667°N, -0.63333°W) by SMU UB-40 with the loss of five of her crew.
 * SS Hilonian (1880) (🇺🇸 United States): World War I: The cargo ship was sunk in the Gulf of Genoa 3 nmi off the mouth of the Albegna by SMU UC-35 with the loss of four of her crew.
 * SS Middlesex (1914) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 150 nmi north west of Tory Island, County Donegal (56.05°N, -12.5°W) by SMU U-30 (Germany) . Her crew survived.
 * SS Pagenturm (1909) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 16 nmi west of Beachy Head, East Sussex (50.66667°N, -0.16667°W) by SMU UB-40 with the loss of four of her crew.
 * SMS S20 : The V1-class destroyer struck a mine and sank in the North Sea with the loss of 25 of her crew.

17 May

 * Alfonso ( undefined): World War I: The sailing vessel was scuttled in the Mediterranean Sea 10 nmi off Denia, Spain (39°N, 0.16667°W) by SMU U-34 (Germany).
 * SS Cito ( undefined): World War I: The coaster was shelled and sunk in the North Sea 20 nmi east of the Noord Hinder Lightship (🇳🇱 Netherlands) by a Kaiserliche Marine torpedo boat with the loss of eleven of her crew.
 * SS Eirini (1903) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Atlantic Ocean 50 nmi south south west of Cadiz, Spain (36.91667°N, -6.51667°W) by SMU U-47 (Germany) . Her crew survived.
 *  Florence Louisa ( undefined): World War I: The schooner was scuttled in the English Channel 8 nmi off The Needles, Isle of Wight by SMU UB-40 . Her crew survived.
 * SS George Pyman (1900) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 130 nmi west of Tearaght Island, County Kerry by SMU U-49 . Her crew survived.
 * Jakoba (🇳🇱 Netherlands): World War I: The fishing vessel was scuttled in the North Sea off Den Helder, North Holland by SMU UC-71 . Her crew survived.
 * SS Kilmaho (1898) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 10 nmi west north west of The Lizard, Cornwall (49.96667°N, -5.31667°W) by SMU UB-20 with the loss of 21 of her crew.
 * SS Lewisham (1898) ( undefined): World War I: The cargo ship was sunk in the Atlantic Ocean west of Ireland by SMU U-46 with the loss of 24 crew. Three survivors were taken as prisoners of war.
 *  Margareta ( undefined): World War I: The four-masted barque was shelled and sunk in the Atlantic Ocean (51°N, -12.3°W).
 * Mercurius (🇳🇱 Netherlands): World War I: The fishing vessel was scuttled in the North Sea 17 nmi north west of Noordwijk, North Holland by SMU UC-71 . Her crew survived.
 * HMS Setter : The R-class destroyer collided with HMS Sylph (1916) and sank in the North Sea off Harwich, Essex.
 * SS Vesterland (1911) (🇸🇪 Sweden): World War I: The cargo ship was sunk in the North Sea 30 nmi east of Lerwick, Shetland Isles, United Kingdom by SMU U-19 (Germany).
 * SS Viken (1916) (🇸🇪 Sweden): World War I: The cargo ship was sunk in the North Sea 20 nmi east of the Orkney Islands, United Kingdom by SMU UC-30.

18 May

 * Adventure ( undefined): World War I: The drifter was shelled and sunk in the Atlantic Ocean south west of the Bishop Rock, Isles of Scilly by SMU UB-20 . Her crew survived.
 * MV Annetta (1911) (🇳🇱 Netherlands): World War I: The coaster was scuttled in the North Sea 40 nmi off IJmuiden, North Holland by SMU UC-71.
 * SS Camberwell (1903) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 6 nmi south east by south of Dunnose Head, Isle of Wight (50.58333°N, -1.05°W) with the loss of seven of her crew.
 * C.E.C.G. ( undefined): World War I: The ketch was scuttled in the English Channel 30 nmi south south east of Start Point, Devon (50.8°N, -4.8°W) by SMU UC-70 . Her crew survived.
 * SS Dromore (1903) ( undefined): World War I: The coaster was shelled and sunk in the English Channel 6 nmi south of St. Martin's Point, Guernsey, Channel Islands by SMU UC-70 . Her crew survived.
 * SS Elford (1915) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 2 nmi south of the Nab Lightship ( undefined) (50.63333°N, -0.96667°W). Her crew survived.
 * Frances M. (🇺🇸 United States): World War I: The sailing vessel was scuttled in the Atlantic Ocean west of Gibraltar (35.48333°N, -8.3°W) by SMU U-47 (Germany) . Her crew survived, but a crew member of U-47 was lost during the scuttling operation.
 * Llandrindod ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 165 nmi north west by west of the Fastnet Rock (51.75°N, -13.96667°W) by SMU U-46 . Her crew survived, but her captain was taken as a prisoner of war.
 * HMT Lucknow : World War I: The naval trawler struck a mine and sank in the English Channel 2 nmi west of the Owers Lightship ( undefined) with the loss of nine of her crew.
 * SS Mary Baird (1908) ( undefined): World War I: The cargo ship struck a mine and sank in the Atlantic Ocean 2.5 nmi west of Pendeen Cove, Cornwall (50.16667°N, -5.73333°W)with the loss of seven of her crew.
 * SS Millicent Knight (1900) ( undefined): World War I: The collier was torpedoed and sunk in the Mediterranean Sea 130 nmi east by south of Malta (35.61667°N, 17.21667°W) by SMU UC-20 with the loss of a crew member.
 * SS Penhale (1911) undefined: World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 72 nmi north west by north of Tearaght Island, County Kerry by SMU U-46  with the loss of a crew member. Her captain was taken as a prisoner of war.
 * Primrose ( undefined): World War I: The drifter was shelled and sunk in the Atlantic Ocean 22 nmi west by south of the Bishop Rock by SMU UB-20 . Her crew survived.

19 May

 * SS Askild (1892) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean 19 nmi north of Ouessant, Finistère, France by SMU UB-20 . Her crew survived.
 *  Elise (🇩🇰 Denmark): World War I: The schooner was sunk in the North Sea (57.46667°N, 3.16667°W) by SMU U-45 with the loss of six crew.
 * SS Erik (1883) (🇸🇪 Sweden): World War I: The coaster was sunk in the Baltic Sea off the coast of Finland (60.25°N, 19.73333°W) by SMU UC-58 . Her crew survived.
 * SS Farnham (1898) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 90 nmi north west of the Fastnet Rock by SMU U-57 with the loss of seventeen crew.
 * SS Kjell (1915) (🇸🇪 Sweden): World War I: The coaster was sunk in the Baltic Sea off the coast of Finland by SMU UC-58 . Her crew survived.
 * SS Kyros (1852) (🇸🇪 Sweden): World War I: The coaster was sunk in the Baltic Sea off the coast of Finland by SMU UC-58 . Her crew survived.
 * SS Mardinian (1913) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 4 nmi south by west of Tabarka Island, Spain (38.08333°N, -0.51667°W) by SMU U-34 (Germany) . Her crew survived.
 * SS Mordenwood (1910) ( undefined): World War I: The cargo ship was sunk in the Mediterranean Sea 90 nmi south east by south of Cape Matapan, Greece (35.03333°N, 22.08333°W) by SMU U-28 (Austria-Hungary) with the loss of 21 of her crew.
 * Olga (🇸🇪 Sweden): World War I: The sailing vessel was sunk in the Baltic Sea off the coast of Finland by SMU UC-58.
 * SS Pauline (1873) (🇸🇪 Sweden): World War I: The coaster was scuttled in the Baltic Sea off Rauma, Finland by SMU UC-58 . Her crew survived.
 * SS Therese (1915) (🇸🇪 Sweden): World War I: The coaster was scuttled in the Baltic Sea off the coast of Finland by SMU UC-58 . Her crew survived.

20 May

 * SS Arnfinn Jarl (1913) (🇳🇴 Norway): World War I: The cargo ship was torpedoed and sunk in the Norwegian Sea 16 nmi west of Holmengrå, Finnmark by SMU U-19 (Germany) . Her crew survived.
 * SS Caspian (1894) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 3 nmi off Cape Cervera, Spain (37.88333°N, -0.36667°W) by SMU U-34 (Germany) with the loss of 25 crew. Three survivors were taken as prisoners of war.
 *  Dana ( undefined): World War I: The brigantine was scuttled in the English Channel 20 nmi north west of Guernsey, Channel Islands by SMU UC-36 . Her crew survived.
 * HMS Lady Patricia : World War I: The Q-ship was sunk in the Atlantic Ocean 90 nmi west of the Skelligs (51.7°N, -13.21667°W) by SMU U-46 with the loss of 31 crew. Two survivors were taken as prisoners of war.
 * Mientji ( undefined): World War I: The sailing vessel was scuttled in the English Channel 25 nmi off the Les Hanois Lighthouse, Guernsey by SMU UC-36 . Her crew survived.
 * SS Normand (1902) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocean 25 nmi north of Ouessant, Finistère, France by SMU UB-20 . Her crew survived.
 * SS Porthkerry (1911) ( undefined): World War I: The collier was torpedoed and sunk in the English Channel 16 nmi west by south of Beachy Head, East Sussex (50.63333°N, -0.13333°W) by SMU UB-40 with the loss of seven of her crew.
 * SS Tijuca (1883) (🇧🇷 Brazil): World War I: The cargo ship was sunk in the Atlantic Ocean 5 nmi south west of the Pierres Noires Lighthouse, Finistère, France by SMU UC-36 . Her crew survived.
 * SS Tycho (1904) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 16 nmi west of Beachy Head by SMU UB-40 with the loss of fifteen of her crew.
 * Voorwarts (🇳🇱 Netherlands): World War I: The sailing vessel was damaged in the North Sea off Terschelling, Friesland by SMU UC-64 . She was towed in to Great Yarmouth, Norfolk, United Kingdom but wad declared a total loss.

21 May

 * HMS Ampleforth (1914) : World War I: The collier was torpedoed and sunk in the Mediterranean Sea 15 nmi west south west of Gozo, Malta (36.16667°N, 13.5°W) by SMU U-65 (Germany) with the loss of four of her crew.
 * SS City of Corinth (1913) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 12 nmi south west of The Lizard, Cornwall (49.9°N, -5.5°W) by SMU UB-31 . Her crew survived.
 * SS Don Diego (1906) ( undefined): World War I: The cargo ship was shelled and sunk in the Mediterranean Sea 40 nmi east by south of Linosa, Italy (35.83333°N, 13.66667°W) by SMU U-65 (Germany) with the loss of five of her crew.
 * SS Ferdinand A. (1888) (🇫🇷 France): World War I: The cargo ship was torpedoed and sunk in the Bay of Biscay 10 to 15 nmi off the Stiff Lighthouse, Ouessant, Finistère (48.66667°N, -5.16667°W) by SMU UC-36 . Her crew survived.
 * SS Jupiter (1901) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 15 nmi west of Beachy Head, East Sussex (50.63333°N, -0.08333°W) by SMU UB-40 with the loss of nineteen of her crew.
 * SS Lanthorn ( undefined): World War I: The cargo ship was captured and scuttled in the North Sea off Whitby, Yorkshire by SMU UB-41 . Her crew survived.
 *  Lynton ( undefined): World War I: The four-masted barque was sunk in the Atlantic Ocean 50 nmi off Queenstown, County Cork, United Kingdom by SMU U-48.
 *  Madura (🇳🇴 Norway): World War I: The barque was scuttled in the Atlantic Ocean 50 nmi south west of Queenstown by SMU U-48 with the loss of two crew.
 *  Saint Michel (🇫🇷 France): World War I: The brigantine was scuttled in the Mediterranean Sea south of the Balearic Islands (37.91667°N, 1.25°W) by SMU U-34 (Germany).
 * HMT Senator : World War I: The naval trawler struck a mine and sank in the Atlantic Ocean off Tory Island, County Donegal (55.25°N, -8.16667°W) with the loss of eleven crew.
 * SMU UC-36 : World War I: The Type UC II submarine was rammed and sunk in the Bay of Biscay off Ouessant (48.7°N, -5.23333°W) by SS Molière (🇫🇷 France) with the loss of all 26 crew.

22 May

 * HMT Epworth : The naval trawler was lost on this date.
 * Jeune Albert (🇫🇷 France): World War I: The fishing vessel was sunk in the Bay of Biscay by SMU UC-21.
 * SS Lanthorn (1889) ( undefined): World War I: The cargo ship was sunk in the North Sea 3 nmi east of Whitby, Yorkshire (54.5°N, -0.48333°W) by SMU UB-41 . Her crew survived.
 * SS Lapa (1872) (🇧🇷 Brazil): World War I: The cargo ship was scuttled in the Atlantic Ocean 130 nmi west south west of Gibraltar (35.46667°N, -8.05°W) by SMU U-47 (Germany).
 * HMT Merse : World War I: The naval trawler struck a mine and sank in the Firth of Clyde 6 nmi south east of Garroch Head, Isle of Bute with the loss of all seventeen crew.
 * SS Milo (1903) ( undefined): The collier collided with another vessel and sank in the English Channel off St. Alban's Head, Dorset.
 * SS Nann Smith (1907) (🇳🇴 Norway): World War I: The cargo ship struck a mine and sank in the Bay of Biscay between Belle Île and Groix, Morbihan, France (47.21667°N, -3.23333°W). Her crew survived.
 * SS Tansan Maru (1894) (🇯🇵 Japan): World War I: The cargo ship was sunk in the Atlantic Ocean 80 nmi west of Annagh Head, County Mayo, United Kingdom (54.16667°N, -12.66667°W) by SMU U-46 . Her crew survived.

23 May

 * Alberdina (🇳🇱 Netherlands): World War I: The sailing vessel was scuttled in the North Sea 25 nmi north west of the Maas Lightship (🇳🇱 Netherlands) by SMU UC-64 . Her crew survived.
 * SS Begona No.3 (1884) (🇪🇸 Spain): World War I: The cagro ship was sunk in the Atlantic Ocean 29 nmi north of Ouessant, Finistère, France (48.91667°N, -5.06667°W) by SMU UC-70 . Her crew survived.
 * Beinir (🇩🇰 Denmark): World War I: The fishing vessel was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * Britannia (🇩🇰 Denmark): World War I: The fishing vessel was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * Else (🇩🇰 Denmark): World War I: The fishing vessel was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * SS Elmmoor (1910) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 36 nmi east by south of Syracuse, Sicily, Italy (36.9°N, 16.15°W) by SMU UC-67 . Her crew survived but her captain was taken as a prisoner of war.
 * SS Elve (1916) (🇳🇱 Netherlands): World War I: The coaster was sunk in the Atlantic Ocean off the north coast of Scotland (59.65°N, -3.33333°W) by SMU U-87.
 * SS England (1906) ( undefined) World War I: The collier was scuttled in the Mediterranean Sea 40 nmi south by east of Cap Bon, Tunisia (36.33333°N, 11.25°W) by SMU U-65 (Germany) with the loss of three crew.
 *  Freden (🇩🇰 Denmark): World War I: The three-masted schooner was sunk in the Atlantic Ocean 60 nmi north west of the Butt of Lewis, United Kingdom by SMU U-30 (Germany) with the loss of two crew.
 * SS Gran (1907) (🇳🇴 Norway): World War I: The cargo ship struck a mine and sank in the North Sea off Ryhope, County Durham, United Kingdom (54.9°N, -1.33333°W). Her crew survived.
 *  Harwood Palmer (🇺🇸 United States): World War I: The schooner was shelled and sunk in the Loire Estuary 6 nmi south west of the Île de la Banche (47.26667°N, -2.5°W) by SMU UC-21 . Her crew were rescued by FRENCH PATROL BOAT Cobra.
 * SS Hector (1903) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 110 nmi north north east of Flamborough Head, Yorkshire, United Kingdom (56.08333°N, 2°W) by SMU U-88 . Her crew survived.
 * SS Lesto (1916) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Bay of Biscay 8 nmi west of the Île du Pilier, Vendée, France (46.95°N, -2.5°W) by SMU UC-21 with the loss of four of her crew.
 * Margrethe (🇩🇰 Denmark): World War I: The fishing vessel was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * Maria Febronia Antonina ( undefined): World War I: The sailing vessel was sunk in the Strait of Sicily by SMU U-65 (Germany).
 * SS Monarch (1878) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 2 nmi east of Seaham, County Durham, United Kingdom by SMU UB-41 with the loss of ten of her crew.
 * Olearia ( undefined): World War I: The fishing vessel was scuttled in the Atlantic Ocean 65 nmi west south west of Suðuroy, Faroe Islands by SMU UC-33 . Her crew survived.
 * Pipitsa (🇬🇷 Greece): World War I: The sailing vessel was scuttled in the Tyrrhenian Sea east of Corsica, France (42°N, 9.98333°W) by SMU UC-35.
 * Sisapon ( undefined): World War I: The trawler was sunk in the Atlantic Ocean 60 nmi west south west of Suðuroy by SMU UC-33 . Her crew survived.
 * Streymoy (🇩🇰 Denmark): World War I: The trawler was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * HMT Tettenhall : World War I: The naval trawler struck a mine and sank in the North Sea off Lowestoft, Suffolk (52.5°N, 1.9°W) with the loss of six of her crew.

24 May

 * Barbara 🇺🇸 United States: World War I: The sailing vessel was set afire and sunk in the Atlantic Ocean 90 nmi west of Gibraltar (36.18333°N, -7.96667°W) by SMU U-47 (Germany) . Her crew survived.
 * SS Belgian (1900) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 50 nmi west of the Fastnet Rock (50.98333°N, -10.7°W) by SMU U-57 with the loss of two crew.
 * SS Biarritz (1914) 🇫🇷 France: World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 50 nmi south east of Malta (35.2°N, 14.26667°W) by SMU U-32 (Germany).
 * Brestir (🇩🇰 Denmark): World War I: The trawler was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 *  Domenico Barone ( undefined): World War I: The barquentine was shelled and damaged in the Mediterranean Sea off Cape Passero, Sicily (36.88333°N, 15.2°W by SMU UC-25 . She was beached but was declared a total loss.
 *  Gudrun (🇳🇴 Norway): World War I: The barque was scuttled in the English Channel 50 nmi south west of Portland Bill, Dorset, United Kingdom by SMU UB-38 . Her crew survived.
 * Isabel Innes (🇩🇰 Denmark): World War I: The fishing vessel was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * SS Jersey City (1914) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 35 nmi north west of Flannan Island, Outer Hebrides (58.5°N, -8.6°W) by SMU U-46 . Her crew survived but her captain was taken as a prisoner of war.
 *  Mcclure ( undefined): World War I: The schooner was scuttled in the Mediterranean Sea 30 nmi east of Cape Carbonara, Sicily, Italy (38.98333°N, 10.25°W) by SMU UC-35 . Her crew survived.
 * HMT Rosevine : The naval trawler was lost on this date.
 *  Sant Antonio di Padova ( undefined): World War I: The brigantine was scuttled in the Mediterranean Sea north west of Sicily (36.4°N, 12.45°W) by SMU U-65 (Germany).
 *  Thyra (🇩🇰 Denmark): World War I: The schooner was scuttled in the English Channel 45 nmi south south east of Start Point, Devon, United Kingdom by SMU UB-38 . Her crew survived.
 * Traveller (🇩🇰 Denmark): World War I: The fishing smack was sunk in the Atlantic Ocean off the Faroe Islands by SMU UC-33 . Her crew survived.
 * SMU UC-24 : World War I: The Type UC II submarine was torpedoed and sunk in the Gulf of Kotor by FRENCH SUBMARINE Circé with the loss of all 26 crew.

25 May

 *  A. H. Frijs (🇩🇰 Denmark): World War I: The barquentine was sunk in the Atlantic Ocean 35 nmi west south west of Suðuroy, Faroe Islands by SMU UC-33 . Her crew survived.
 * Argentina ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20.
 * Diego Russo ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea south west of Policastro Bussentino, Campania by SMU U-65 (Germany).
 * SS Glyg (1889) (🇳🇴 Norway): World War I: The coaster was sunk in the Atlantic Ocean 17 nmi north north west of Muckle Flugga, Shetland Islands, United Kingdom by SMU UC-33 . Her crew survived.
 * HMS Hilary (1908) : World War I: The armed merchant cruiser was torpedoed and sunk in the Atlantic Ocean 40 nmi west of the Shetland Islands (60.55°N, -3°W) by SMU U-88 with the loss of four of her crew.
 * Ida ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20.
 * SS Kohinur (1905) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 150 nmi north west of Alexandria, Egypt (33.33333°N, 29.83333°W) by SMU U-38 with the loss of 37 crew.
 *  Magnus Manson (🇺🇸 United States): World War I: The five-masted schooner was set afire and sunk in the Atlantic Ocean 50 nmi west by south of Cape St. Vincent, Spain by SMU U-47 (Germany) . Her crew survived.
 * Natale Monaco ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea by SMU U-65 (Germany).
 * Nicolino ( undefined): World War I: The sailing vessel was sunk in the Gulf of Genoa by SMU UC-35.
 * Rosina R. ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea by SMU U-65 (Germany).
 * SS Sjaelland (1872) ( undefined): World War I: The cargo ship was shelled and sunk in the English Channel 18 nmi east by north of Start Point, Devon by SMU UC-66 with the loss of a crew member.
 * Unione Salvatore ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20.
 * Vincenzino C. ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea by SMU U-65 (Germany).
 *  Whinlatter (🇳🇴 Norway): World War I: The barque was sunk in the Atlantic Ocean (61.06667°N, -2.88333°W) by SMU UC-33 . Her crew survived.

26 May

 * Abd es Salaam (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily, Italy by SMU UC-20.
 * SS Agragas (1880) ( undefined): World War I: The cargo ship was sunk in the Mediterranean Sea off Syrte, Libya by SMU UC-73 . Her crew survived.
 * Angelo Padre ( undefined): World War I: The sailing vessel was sunk in the Tyrrhenian Sea off Policastro Bussentino, Campania by SMU U-65 (Germany).
 * SS Aristides (1884) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Bay of Biscay 5 nmi north north west of Cabo del Ajo, Spain by SMU UC-21 . Her crew survived.
 * SS Carlos de Eizaguirre (🇪🇸 Spain): World War I: The ship struck a mine and sank off Cape Town, South Africa with the loss of 84 of the 108 people on board.
 * Dandolo (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20.
 *  Detlef Wagner ( undefined): World War I: The barquentine was shelled and sunk in the Atlantic Ocean 5 nmi west of Ar Men, Finistère, France by SMU UC-72 . Her crew survived.
 * SS Dorothy (1914) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Mediterranean Sea 45 nmi off Cap d'Armi by SMU UB-43.
 *  : World War I: The hospital ship was torpedoed and sunk in the Mediterranean Sea 50 nmi north of Bône, Algeria (37.75°N, 7.6°W) by SMU UC-67 with the loss of seven crew. Survivors were rescued by HMS Cameleon (1910).
 * SS Holmesbank (1906) ( undefined): World War I: The collier was shelled and sunk in the Mediterranean Sea 90 nmi north by west of Alexandria, Egypt (32.43333°N, 29.5°W) by SMU U-38 . Her crew survived.
 *  Lucipara ( undefined): World War I: The barque was sunk in the Atlantic Ocean 45 nmi north west of Inishtrahull Island, County Donegall, United Kingdom (55.91667°N, -8.41667°W) by SMU U-87.
 * Manoubia (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20.
 * Messaouda (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20.
 * SS Norhaug (1899) (🇳🇴 Norway): World War I: The cargo ship struck a mine and sank in the Bay of Biscay 10 nmi west of Saint-Nazaire, Loire-Atlantique, France (47.21667°N, -2.55°W) with the loss of five of her crew.
 * SS Norway (1910) (🇳🇴 Norway): World War I: The cargo liner was sunk in the Norwegian Sea 11 nmi west of Holmengrå, Finnmark by SMU U-19 (Germany) . All passengers and crew survived.
 *  Risorgimento ( undefined): World War I: The schooner was scuttled in the Mediterranean Sea south of Sardinia (38.21667°N, 9.76667°W) by SMU UC-35.
 *  Saint Hubert (🇫🇷 France): World War I: The barque was scuttled in the English Channel 6 nmi north north west of Cap La Hague, Manche by SMU UC-45.
 *  Saint Mirren ( undefined): World War I: The full-rigged ship was shelled and sunk in the Atlantic Ocean 45 nmi north west of Inistrahull Island (55.91667°N, -8.41667°W) by SMU U-87 . Her crew survived.
 * San Francesco ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Sicily by SMU UC-20 . Her crew survived.
 * SS Umaria (1914) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Tyrrhenian Sea 20 nmi south west by south of Policastro Bussentino (39.8°N, 15.2°W) by SMU U-65 (Germany) with the loss of five crew. Three survivors were taken as prisoners of war.
 * SMS V84 : World War I: The V25-class destroyer struck a mine and sank in the North Sea with the loss of five of her crew.

27 May

 * Beatrice ( undefined): World War I: The sailing vessel was sunk in the Strait of Sicily by SMU U-33 (Germany).
 * SS Boldwell (1901) ( undefined): World War I: The collier was torpedoed and sunk in the Mediterranean Sea 35 nmi north east of Linosa, Italy (36.2°N, 13.4°W) by SMU UC-20 with the loss of three of her crew.
 * SS Dartmoor (1892) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 35 nmi south east of the Fastnet Rock (51.15°N, -8.76667°W) by SMU UC-50 with the loss of 25 of her crew.
 *  Debora (🇩🇰 Denmark): World War I: The three-masted schooner was captured and scuttled in the North Sea 70 nmi west south west of Lista, Vest-Agder, Norway (57.93333°N, 5.81667°W) by SMU U-19 (Germany) . Her crew survived.
 * SS Efstathios (1907) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Bay of Biscay 15 nmi off Cape Penus by SMU UC-21.
 *  Général de Boisdeffre (🇫🇷 France): World War I: The barque was sunk in the Atlantic Ocean 70 nmi west of Ouessant, Finistère by SMU UC-70 with the loss of all hands.
 *  Luigi ( undefined): World War I: The brigantine was sunk in the Mediterranean Sea off Ustica (38.96667°N, 15.81667°W) by SMU U-65 (Germany).
 * Maria Giuseppe ( undefined): World War I: The sailing vessel was sunk off the south coast of Italy by SMU U-65 (Germany).
 * Michele Constantino ( undefined): World War I: The sailing vessels was sunk in the Strait of Sicily by SMU U-33 (Germany) . Her crew survived.

28 May

 * SS Ancona (1888) ( undefined): World War I: The cargo ship was sunk in the Atlantic Ocean 110 nmi west south west of Ouessant, Finistère, France by SMU UC-70 with the loss of all hands.
 * SS Antinoe (1907) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 150 nmi west south west of the Bishop Rock, Isles of Scilly (48.83333°N, -10.16667°W) by SMU U-86 with the loss of 21 of her crew.
 * Asters (🇳🇴 Norway): World War I: The passenger ship, a barque, was torpedoed and sunk in the Atlantic Ocean 150 nmi west by north of the Isles of Scilly (50°N, -7°W) by SMU UC-55 . All on board survived.
 * SS Hiram (1890) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Bay of Biscay 10 nmi off Cape Vilano, Spain by SMU UC-21 . Her crew survived.
 * SS Limerick (1898) ( undefined): World War I: The refrigerated cargo liner was torpedoed and sunk in the Atlantic Ocean 140 nmi west of the Bishop Rock (48.88333°N, -9.75°W) by SMU U-86 with the loss of eight of her crew.
 * Nuevo S. Giovanni ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Cape Passero, Sicily by SMU UC-25.
 * S. Andrea ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea off Cape Passero by SMU UC-25.
 *  Teie (🇳🇴 Norway): World War I: The full-rigged ship wasscuttled in the Atlantic Ocean 60 nmi south of the Fastnet Rock (50.46667°N, -9.33333°W) by SMU UC-45 . Her crew survived.
 * SS Turid (1904) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 25 nmi north east by east of Peterhead, Aberdeenshire, United Kingdom by SMU UC-44 . Her crew survived.
 * SS Urna (1903) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Bay of Biscay 10 nmi east by north of Cabo Prior, Spain by SMU UC-21 . Her crew survived.
 * SS Waldemar (1904) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Bay of Biscay 2.5 nmi off Cabo Moras, Spain (43.78333°N, -7.46667°W) by SMU UC-21 . Her crew survived.

29 May

 * Aghia Tom Aghion (🇬🇷 Greece): World War I: The sailing vessel wassunk in the Mediterranean Sea north of Crete by SMU UC-74.
 *  Argo (🇸🇪 Sweden): World War I: The schooner was sunk in the Atlantic Ocean north west of the Hebrides (59.1°N, -8.81667°W) by SMU U-69 . Her crew survived.
 * SS Ashleaf (1916) ( undefined): World War I: The tanker was torpedoed and sunk in the Atlantic Ocean 150 nmi west of the Bishop Rock, Isles of Scilly (48.66667°N, -9.5°W) by SMU U-88 . Her crew survived.
 * SS Clan Murray (1897) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 40 nmi west by south of the Fastnet Rock(50.95°N, -10.35°W) by SMU UC-55 with the loss of 64 lives. One survivor was taken as a prisoner of war.
 *  Consul N. Nielsen (🇩🇰 Denmark): World War I: The barque was sunk in the Atlantic Ocean north west of the Hebrides by SMU U-69 . Her crew survived.
 * SS Fridtjof Nansen (1881) (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea east of the Shetland Islands, United Kingdom (60.51667°N, 1.68333°W) by SMU U-28 (Germany) . Her crew survived.
 *  Ines (🇸🇪 Sweden): World War I: The brig was sunk in the Atlantic Ocean north west of the Hebrides (58.98333°N, -9.4°W) by SMU U-69 . She was manned by a British prize crew of four, who were taken as prisoners of war.
 * Karna (🇳🇴 Norway): World War I: The sailing vessel was scuttled in the North Sea 50 nmi west of Kirkenes, Vest-Agder (61.35°N, -0.13333°W) by SMU U-28 (Germany) . Her crew survived.
 * Kirikos (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea north of Crete by SMU UC-74.
 *  Kodan (🇳🇴 Norway): World War I: The three-masted schooner was scuttled in the North Sea 50 nmi east of the Out Skerries, Shetland Islands, United Kingdom by SMU U-28 (Germany) . Her crew survived.
 * SS Oswego (1916) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 175 nmi west of the Bishop Rock, Isles of Scilly (48.73333°N, -10.25°W) by SMU U-86 . Her crew survived.
 * SS Yarra (1883) (🇫🇷 France): World War I: The troopship was torpedoed and sunk in the Mediterranean Sea 20 nmi north west of Cape Sidero, Crete (35.66667°N, 25.58333°W) by SMU UC-74 with the loss of at least 16 lives. Survivors were rescued by FRENCH DESTROYER Arbalete, FRENCH GUNBOAT La Dedaigneuse (both ) and HMS Lily (1915).

30 May

 * SS Bathurst (1893) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 90 nmi west of the Bishop Rock, Isles of Scilly (49.38333°N, -8.71667°W) by SMU U-87 . Her crew survived.
 * SS Corbet Woodall (1908) ( undefined): World War I: The coaster struck a mine and sank in the English Channel 1.5 nmi east of the Nab Lightship ( undefined). Her crew survived.
 * SS Hanley (1902) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 95 nmi west of the Bishop Rock (49.38333°N, -8.71667°W) by SMU U-87 with the loss of a crew member.
 * HMT Ina William : World War I: The naval trawler struck a mine and sank in the Atlantic Ocean 2 nmi south of the Bull Rock Lighthouse (51.71667°N, -10.3°W) with the loss of twelve of her crew.
 * SS Lisbon (1910) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 5 nmi south of the Royal Sovereign Lightship ( undefined) (50.63333°N, 0.33333°W) with the loss of a crew member.
 * SS Sørland (1896) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Atlantic Ocea (46.18333°N, -8.33333°W) by SMU UC-21 . Her crew survived.

31 May

 *  Dirigo (🇺🇸 United States): World War I: The four-masted barque was sunk in the Atlantic Ocean 6 nmi south west of the Eddystone Lighthouse (50.15°N, -4.46667°W) by SMU UB-23 with the loss of a crew member.
 * SS Esneh (1908) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 190 nmi north west by west of Tory Island, County Donegal by SMU U-69 . Her crew survived.
 *  Jeanne Cordonnier (🇫🇷 France): World War I: The barque was shelled and sunk in the Atlantic Ocean 150 nmi west of the Isles of Scilly, United Kingdom by SMU U-88 with the loss of a crew member.
 * SS Miyazaki Maru (1909) (🇯🇵 Japan): World War I: The passenger ship was sunk in the Atlantic Ocean 150 nmi west of the Isles of Scilly (49.08333°N, -9.58333°W) by SMU U-88.
 * SS N. Hadzikyiakos (1904) (🇬🇷 Greece): World War I: The cargo ship was sunk in the Atlantic Ocean (48°N, -12°W) by SMU U-86.
 * Ninotto ( undefined): World War I: The sailing vessel was sunk in the Strait of Sicily (36.58333°N, 11.1°W) by SMU UC-25.
 * SS Ozarda (1913) ( undefined): World War I: The cargo ship struck a mine and was damaged in the Mediterranean Sea off Port Said, Egypt. She was beached but was later refloated, repaired and returned to service.
 * SS Rosebank (1901) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 120 nmi north of Benghazi, Libya (34.15°N, 19.58333°W) by SMU UC-73 with the loss of two of her crew. Her captain was taken as a prisoner of war.

Unknown date

 * SMU UB-36 : World War I: The Type UB II submarine was lost on active service after 9 May. Possibly struck a mine and sank in the North Sea off West Flanders, Belgium. All 22 crew lost.