List of shipwrecks in May 1918

The list of shipwrecks in May 1918 includes ships sunk, foundered, grounded, or otherwise lost during May 1918.

1 May

 * HMS Blackmorevale (1917) : World War I: The Hunt-class minesweeper struck a mine and sank in the North Sea off Tod Head, Aberdeenshire with the loss of 26 of her 74 crew.
 * SS Era (1888) (🇦🇺 Australia): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea off Cape Ténès, Algeria (36.75°N, 1.93333°W) by SMU U-32 (Germany) with the loss of twelve crew.
 * SS Matiana (1894) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea off Tunisa, Tunisia (37.25°N, 10.08333°W) by SMU UC-27 . Her crew survived.
 * Nikolaos (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea off the coast of Egypt (31.51667°N, 29.23333°W) by SMU UC-74.
 * MV Samsö (1876) (🇩🇰 Denmark): World War I: The coaster struck a mine and sank in the North Sea 3 nmi east by south of the Roker Lighthouse, County Durham, United Kingdom. Her crew survived.
 * San Nicola ( undefined): World War I: The sailing vessel was sunk in the Mediterranean Sea (35.96667°N, 23.83333°W) by SMU U-27 (Austria-Hungary) . Her crew survived.
 * RUSSIAN DESTROYER Zavetni : World War I: The Boiki-class destroyer was scuttled at Sevastopol.

2 May

 * HMT Antares II : The naval trawler was lost on this date in the Mediterranean Sea.
 * SS Flawyl (1906) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 30 nmi east south east of Pantelleria, Italy (36.68333°N, 12.7°W) by SMU UB-52 with the loss of a crew member.
 * SS Franklyn (1904) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 65 nmi east by north of Port Mahon, Spain (40.4°N, 5.68333°W) by SMU UB-48 . Her crew survived.
 * SS Girdleness (1905) ( undefined): World War I: The cargo ship was torpedoed and sunk in Bude Bay (50.9°N, -4.68333°W) by SMU U-60 with the loss of two crew.
 * SS Medora (1912) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Irish Sea 11 nmi south west of the Mull of Galloway, Wigtownshire by SMU U-86 . Her crew survived, but three of them were taken as prisoners of war.
 * SS Thorsa (1884) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 3 nmi north north west of the Pendeen Lighthouse, Cornwall (50.2°N, -5.73333°W) by SMU UB-103 . Her crew survived.
 * SS Tyler (1913) (🇺🇸 United States): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 65 nmi east by north of Port Mahon (40.4°N, 5.68333°W) by SMU UB-48 with the loss of eleven of her crew.
 * SMU UB-31 : World War I: The Type UB II submarine struck a mine and sank in the Strait of Dover (51.01667°N, 1.26667°W) with the loss of all 22 crew.
 * SS Unity (1902) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 9 nmi south east of Folkestone, Kent by SMU UB-57 with the loss of twelve of her crew.
 * SS Valdivia (1905) (🇫🇷 France): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 45 nmi south west of Cape Spartel, Morocco (35.11667°N, -6.5°W) by SMU UB-70 with the loss of two of her crew.

3 May

 * SMS G9 : World War I: The V1-class destroyer struck a mine and sank in the North Sea with the loss of 31 of her crew.
 * Il Francesco ( undefined): World War I: The sailing vessel was shelled and sunk in the Tyrrhenian Sea 8 nmi east of Monte Santo, Sardinia (40.16667°N, 9.83333°W) by SMU UC-35.
 * Panaghia (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (35.81667°N, 26.48333°W) by SMU U-27 (Austria-Hungary) . Her crew survived.
 * SS Vasilefs Georgios (1904) (🇬🇷 Greece): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 3 nmi north east of Pendeen, Cornwall, United Kingdom (50.21667°N, -5.66667°W) by SMU UB-103.

4 May

 * SMS A71 : World War I: The A56-class torpedo boat struck a mine and sank in the North Sea with the loss of six of her crew.
 * SS Polbrae (1896) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 4.5 nmi off Bude, Cornwall by SMU U-60 with the loss of two crew.

5 May

 * Aghios Johannis (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea north of Crete by SMU U-33 (Germany).
 * SS Alberto Treves (1900) ( undefined): World War I: The cargo ship was damaged in the Mediterranean Sea off Cartagena, Murcia, Spain by SMU U-38 and was beached. She was subsequently refloated, repaired and returned to service.
 * Carrione ( undefined): World War I: The sailing vessel was shelled and sunk in the Gulf of Genoa 5 nmi west south west of the Capo Mele Lighthouse, Liguria (43.86667°N, 8.5°W) by SMU UC-35.
 * HMS David Gillies : The naval tug was lost in the Mediterranean Sea on this date.
 * Kyarra ( undefined): World War I: The cargo liner was torpedoed and sunk in the English Channel off Swanage, Dorset by SMU UB-57 with the loss of six crew.
 * SS Petersham ( undefined): The cargo ship collided with another vessel and sank.
 * HMS Rhododendron (1917) : World War I: The Anchusa-class sloop) was sunk in the North Sea (59.55°N, -2.83333°W) by SMU U-70 with the loss of fifteen of her 93 crew.
 * Sayeda (🇪🇬 Egypt): World War I: The sailing vessel was sunk in the Mediterranean Sea off the coast of Egypt by SMU UC-74.
 *  Tommi ( undefined): World War I: The schooner was shelled and sunk in the Irish Sea between the Calf of Man and Chicken Rock, Isle of Man by SMU U-86 with the loss of four of her crew.
 * SMU UB-70 : World War I: The Type UB III submarine was last reported in the Mediterranean Sea east of Gibraltar. Subsequently lost with all 33 crew.
 * SMU UB-119 : World War I: The Type UB III submarine was rammed and sunk in the Atlantic Ocean off Rathlin Island, County Donegal, United Kingdom (55.26667°N, -6.4°W) by SS Green Island (flag unknown) with the loss of all 34 crew.

6 May

 * Aghios Dimitrios (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (35.7°N, 25.41667°W) by SMU U-27 (Austria-Hungary) . Her crew survived.
 * Evangelistria (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (35.63333°N, 25.21667°W) by SMU U-27 (Austria-Hungary) . Her crew survived.
 * SS Leeds City (1908) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Irish Sea 5 nmi east by south of the Skulmartin Lightship ( undefined) by SMU U-86 . Her crew survived.
 * SS Sandhurst (1897) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Irish Sea 6 nmi north west by west of Corsewall Point, Wigtownshire (54.96667°N, -5.41667°W) by SMU UB-72 with the loss of twenty of her crew.
 * Taxiarchis (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (35.63333°N, 25.21667°W) by SMU U-27 (Austria-Hungary) . Her crew survived.

7 May

 * HM CMB-10 : The Coastal Motor Boat was lost on this date.
 * SS Nantes (1917) ( undefined): World War I: The cargo ship was torpedoed and sunk in the North Sea 83 nmi east south east of Fair Isle by SMU U-105 . Her crew survived.
 * SS Saxon (1881) ( undefined): World War I: The cargo ship was torpedoed and sunk in the North Sea 83 nmi east south east of Fair Isle by SMU U-105 with the loss of 22 crew.

8 May

 * SS Constantia (1890) ( undefined): World War I: The coaster was torpedoed and sunk in the North Sea 2 nmi off Robin Hood's Bay, Yorkshire by SMU UB-21 with the loss of three of her crew.
 * SS Dux (1904) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 7 nmi north west of the Godrevy Lighthouse, Cornwall (50.26667°N, -5.53333°W) by SMU U-54 . Her crew survived.
 * SS Ingleside (1910) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 80 nmi off Algiers, Algeria by SMU U-38 with the loss of eleven crew.
 * SS Princess Dagmar (1907) ( undefined): World War I: The coaster was torpedoed and sunk in the Bristol Channel by SMU U-54 with the loss of all 24 crew.
 *  Thoralf (🇩🇰 Denmark): World War I: The barque was scuttled in the Irish Sea 20 nmi south east of the Coningbeg Lightship ( undefined) (51.93333°N, -5.91667°W) by SMU UB-65 . Her crew survived.
 * SMU U-32 (Germany) :World War I: The Type U 31 submarine was depth charged and sunk in the Mediterranean Sea north west of Malta (36.11667°N, 13.46667°W) by HMS Wildflower with the loss of all 41 crew.

9 May

 * SS Baron Ailsa (1912) ( undefined): World War I: The collier was torpedoed and sunk in the Irish Sea 18 nmi west north west of the Smalls Lighthouse by SMU UB-72 with the loss of ten of her crew.
 * SS Deipara (1886) ( undefined): World War I: The cargo ship was sunk in the Mediterranean Sea off Cape Camarat, Var, France by SMU UC-35 with the loss of eight of her crew.
 * SS Enrichetta (1910) ( undefined): World War I: The cargo ship was sunk in the Atlantic Ocean (35.48333°N, -12.36667°W) by SMU U-153 . Her crew survived.
 * SMU UC-78 : World War I: The Type UC II submarine was rammed and sunk in the English Channel off Cherbourg, Manche, France by SS Queen Alexandra ( undefined).

10 May

 * SS Amplegarth (1910) ( undefined): World War I: The cargo ship struck a mine and sank in the English Channel 1 nmi west south west of Dover, Kent. Her crew survived.
 * SS Anboto Mendi (1907) (🇪🇸 Spain): World War I: The cargo ship was sunk in the North Sea off Robin Hood's Bay, Yorkshire, United Kingdom by SMU UB-21.
 * SS Erich Lea (🇳🇴 Norway): World War I: The cargo ship was sunk in the North Sea 6 nmi south east of Whitby, Yorkshire by SMU UB-107 . Her crew survived.
 * SS Itinda (1900) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 40 nmi north of Matra Susa, Libya (32.4°N, 21.8°W) by SMU U-47 (Austria-Hungary) with the loss of a crew member.
 * HMML 254 : The motor launch was lost on this date.
 * SS Szechuen (1895) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 60 nmi north by east of Port Said, Egypt (32°N, 32.76667°W) by SMU UB-51 with the loss of nine of her crew.
 * SMU UB-16 : World War I: The Type UB I submarine was torpedoed and sunk in the North Sea off Harwich, Essex, United Kingdom (52.1°N, 2.01667°W) by HMS E34 with the loss of thirteen of her fourteen crew.
 * HMS Vindictive (1897) : World War I: Second Ostend Raid: The Arrogant-class cruiser was sunk as a blockship at Ostend, West Flanders, Belgium.
 * SS Wileysike (1888) ( undefined): World War I: The cargo ship was torpedoed and sunk in St. George's Channel 8 nmi off St. Ann's Head, Pembrokeshire by SMU U-54 with the loss of four crew.

11 May

 * Clan Mackay ( undefined): The 6,580 grt Clan Line vessel was in collision with an unnamed vessel in the Bay of Biscay and sank.
 * Gigilla ( undefined): World War I: The sailing vessel was sunk in the Strait of Messina by SMU UC-52.
 * SS Gothia (1883) (🇸🇪 Sweden): World War I: The cargo ship was sunk in the North Sea 8 nmi north east of Hartlepool, County Durham, United Kingdom by SMU UB-21 . Her crew survived.
 * HMT Holly III : The naval trawler was lost on this date.
 * Massouda ( undefined): World War I: The sailing vessel was scuttled in the Mediterranean Sea 50 nmi north of Marsa Matruh, Egypt by an enemy submarine.
 * Michail (Flag of Russian SFSR.svg Russia): World War I: The fishing vessel was sunk in the Arctic Ocean 8 nmi east north east of Svyatoy Nos by SMU U-22 (Germany) . Her crew survived.
 * SS San Andres (1911) (🇳🇴 Norway): World War I: The cargo ship was sunk in the Irish Sea 100 nmi west of Lundy Island, Devon, United Kingdom (51.38333°N, -7.88333°W) by SMU U-86 with the loss of two of her crew.
 * SS Sant Anna (1910) : World War I: The troopship was sunk in the Mediterranean Sea south of Pantelleria, Italy (37.06667°N, 11.6°W) by SMU UC-54 with the loss of 605 lives.
 * SS Suzette Fraissinet (1892) (🇫🇷 France): World War I: The cargo ship was sunk in the Mediterranean Sea 37 nmi south of Cape Spartivento, Italy by SMU UB-52 . Her crew survived.
 * SMU U-154 : World War I: The Type U 151 submarine was torpedoed and sunk in the Atlantic Ocean (36.85°N, -11.83333°W) by HMS E35 with the loss of all 77 crew.
 * SS Verona (1908) ( undefined): World War I: The troopship was sunk in the Strait of Messina (37.06667°N, 16.31667°W) by SMU UC-52 with the loss of 880 lives.

12 May

 * SS Haslingden (1895) ( undefined): World War I: The cargo ship was torpedoed and sunk in the North Sea 7 nmi off Seaham, County Durham by SMU UB-21  with the loss of eleven of her crew.
 * SS Inniscarra (1903) ( undefined): World War I: The passenger ship was torpedoed and sunk in the Atlantic Ocean 10 nmi south east of Ballycottin Island, County Cork by SMU U-86 with the loss of 28 of her crew.
 * Kong Raud (🇳🇴 Norway): World War I: The trawler was sunk in the Barents Sea 32 nmi north east of Svyatoy Nos, Russia by SMU U-22 (Germany) . Her crew survived.
 * SS Omrah (1899) ( undefined): World War I: The passenger ship was torpedoed and sunk in the Mediterranean Sea 40 nmi south by west of Cape Spartivento, Sicily, Italy by SMU UB-52 with the loss of a crew member.
 * SS Pax (1907) (🇫🇷 France): World War I: The coaster was torpedoed and sunk in the Mediterranean Sea 7 nmi off Cape Camarat, Var 43.13333°N, 6.7°W by SMU UC-35 with the loss of fifteen of her crew.
 * Tennes (🇳🇴 Norway): World War I: The trawler was sunk in the Barents Sea 20 nmi north east of Svyatoy Nos by SMU U-22 (Germany).
 * SS Togo (1882) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea (43.16667°N, 6.6°W) by SMU UC-35 with the loss of a crew member.
 * SMU U-103 : World War I: The Type U 57 submarine was rammed and sunk in the Atlantic Ocean (49.26667°N, -4.85°W) by RMS Olympic ( undefined) with the loss of nine of her 40 crew. Survivors were rescued by USS Davis (DD-65).
 * SMU UB-72 : World War I: The Type UB III submarine was depth charged and sunk in the English Channel (50.13333°N, -2.68333°W) by HMS D4 ( with the loss of 34 of her crew.
 * Vea (🇳🇴 Norway): World War I: The trawler was sunk in the Barents Sea 20 nmi east north east of Svyatoy Nos by SMU U-22 (Germany) . Her crew survived.
 * SS Vimiera (1914) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 16 nmi west south west of Lampedusa, Italy (35.38333°N, 12.31667°W) by SMU UC-54 . Her crew survived.

13 May

 * Agnes (🇸🇪 Sweden): World War I: The trawler struck a mine and sank in the Skaggerak off Skagen, Denmark with the loss of all but two of her crew.
 * HMT Balfour : The naval trawler collided with SS Nidd ( undefined and sank in the English Channel 5 nmi west south west of the Royal Sovereign Lightship ( undefined). Her crew were rescued by Nidd.
 * SS Esperanza de Larrinaga (1907) ( undefined): World War I: The cargo ship was torpedoed and damaged in the Irish Sea (55.81667°N, -7.41667°W) by SMU UB-65 with the loss of a crew member. She was beached in Lough Swilly.
 * Julia (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (36.58333°N, 22.16667°W) by SMU U-32 (Austria-Hungary) . Her crew survived.
 * HMT Loch Naver : World War I: The naval trawler struck a mine and sank in the Aegean Sea (37.83333°N, 24.43333°W) with the loss of thirteen of her crew.
 * SMU UB-114 : The Type UB III submarine sank at Kiel, Schleswig-Holstein with the loss of seven of her crew. She was later raised.
 * USS Zaanland (ID-2746) : The cargo ship was rammed and sunk in the Atlantic Ocean by USS Hisko (ID-1953) . Her crew were rescued by USS Munalbro (1916) (🇺🇸 United States).

14 May

 * SMS A72 : World War I: The A56-class torpedo boat struck a mine and sank in the North Sea with the loss of 25 of her crew.
 *  Embla (🇩🇰 Denmark): World War I: The schooner was scuttled in the North Sea south west of Skudesnes, Rogaland, Norway (57.75°N, 3.5°W) by SMU U-101 . Her crew survived.
 * HMS Phoenix (1911) : World War I: The Acheron-class destroyer was torpedoed and sunk in the Adriatic Sea off Vlorë, Albania by SMU U-27 (Austria-Hungary) with the loss of two of her 72 crew.
 * Stairs (🇳🇴 Norway): World War I: The trawler was sunk in the Barents Sea 10 nmi north of Vaidaguada, Russia by SMU U-22 (Germany).
 * SS Woolston (1900) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 1.5 nmi off Syracuse, Sicily, Italy (37.5°N, 12.33333°W) by SMU UC-52 with the loss of nineteen of her crew.

15 May

 * SS Villa de Soller (1903) (🇪🇸 Spain): World War I: The coaster was sunk in the Mediterranean Sea off Hyères, Var, France by SMU UC-35 . Her crew survived.
 * SS War Grange ( undefined): World War I: The cargo ship was torpedoed and damaged in the Atlantic Ocean 7 nmi off Town Head, Cornwall (50.46667°N, -5.11667°W) by SMU U-55 with the loss of five crew. She was beached at Newquay but was later salvaged.

16 May

 * SS Fyedor Chizhov (1902) (Flag of Russian SFSR.svg Russia): World War I: The coaster was sunk in the Barents Sea off Vaidaguada by SMU U-22 (Germany).
 * SS Heron Bridge (1918) ( undefined): World War I: The collier was torpedoed and sunk in the Atlantic Ocean 320 nmi east by north of São Miguel Island, Azores, Portugal (38.81667°N, -18.43333°W) by SMU U-62  with the loss of a crew member.
 * SS Llancarvan (1904) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 370 nmi east of São Miguel Island (38.4°N, -17.3°W) by SMU U-62 . Her crew survived.
 * Mansoura (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea north of Port Said, Egypt (32.25°N, 31.58333°W) by SMU UB-51.
 * FRENCH TRAWLER Marie Frédérique : World War I: The naval trawler struck a mine and sank in the Mediterranean Sea north of Cap de Garde, Algeria (37.03333°N, 7.86667°W) with the loss of eighteen of her crew.
 * Polarstrømmen (🇳🇴 Norway): World War I: The trawler was sunk in the Barents Sea 6 nmi north of Vaidaguada, by SMU U-22 (Germany) . Her crew survived.
 * HMT Silvery Harvest : The naval trawler collided with another vessel and sank in the English Channel off Berry Head, Devon with some loss of life.
 * SS Tagona (1908) (🇨🇦 Canada): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 5 nmi west south west of Trevose Head, Cornwall, United Kingdom 50.48333°N, -5.11667°W) by SMU U-55 with the loss of eight crew.
 * SS Tartary (1901) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Irish Sea 8 nmi east north east of the Skulmartin Lightship ( undefined) by SMU U-86 . Her crew survived.
 * SMU UC-35 . World War I: The Type UC II submarine was shelled and sunk in the Mediterranean Sea south west of Sardinia, Italy by FRENCH PATROL BOAT Ailly with the loss of twenty of her 25 crew.
 * SS Yturri Bide (1877) (🇪🇸 Spain): World War I: The coaster was sunk in the Atlantic Ocean north east of the Tuskar Rock, Ireland (52.45°N, -5.58333°W) by SMU UB-118.

17 May

 * SS Mavisbrook (1912) ( undefined): World War I: The collier was torpedoed and sunk in the Mediterranean Sea 50 nmi south east by south of Cabo de Gata, Andalusia, Spain (36.08333°N, -1.58333°W) by SMU UB-50 with the loss of eighteen crew.
 * SS Motricine (1913) (🇫🇷 France): World War I: The tanker was sunk in the Atlantic Ocean 72 nmi north east of Ouessant, Finistère (49.31667°N, -7.48333°W) by SMU U-55 . Her captain was taken as a prisoner of war.
 * Pietro Brizzolari ( undefined): World War I: The sailing vessel was sunk in the Strait of Messina by SMU UC-52.
 * SS Sculptor (1912) ( undefined): World War I: Convoy GB 35: The cargo ship was torpedoed and damaged in the Mediterranean Sea 60 nmi north west of Oran, Algeria by SMU U-39 . She was beached at Mers-el-Kebir, Libya The bow section of the ship was destroyed by an explosion during salvage operations and she was abandoned as a total loss.
 * SMU UC-35 : World War I: The Type UC II submarine was shelled and sunk in the Mediterranean Sea south west of Sardinia, Italy (39.8°N, 7.7°W) by FRENCH PATROL VESSEL Ailly with the loss of twenty of her 25 crew.

18 May

 * FRENCH DESTROYER Catapulte : The Arquebuse-class destroyer collided with SS Warrimoo ( undefined and sank in the Mediterranean Sea off Bône, Algeria.
 * HMS Chesterfield (1913) : World War I: The fleet messenger was torpedoed and sunk in the Mediterranean Sea 42 nmi north east by east of Malta (36.28333°N, 15.21667°W) by SMU UC-52 with the loss of four of her crew.
 * SS Denbigh Hall (1906) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 90 nmi) west south west of the Bishop Rock, Isles of Scilly (49°N, -8.03333°W) by SMU U-55 . Her crew survived.
 * SS Hurunui (1912) ( undefined): World War I: The cargo ship was torpedoed and sunk in the English Channel 48 nmi south by east of The Lizard, Cornwall (49.13333°N, -5°W) by SMU U-94 with the loss of a crew member.
 * SS John G. Mccullough (1890) (🇺🇸 United States): World War I: The cargo ship was torpedoed and sunk in the Bay of Biscay 8 nmi south of the Île d'Yeu (46.58333°N, -2.26667°W) by SMU UB-74 with the loss of a crew member.
 * Mabrouka (🇫🇷 France): World War I: The 25-ton sailing vessel was sunk in the Mediterranean Sea north of Port Said, Egypt by SMU UB-51.
 * Mabrouka (🇫🇷 France): World War I: The 45-ton sailing vessel was sunk in the Mediterranean Sea north of Port Said by SMU UB-51.
 * Maria (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea north of Port Said by SMU UB-51.
 * Menewar (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea by SMU UB-51.
 * Ninetta ( undefined): World War I: The sailing vessel was shelled and sunk in the Mediterranean Sea 22 nmi south east by south of Cape Passero, Sicily by SMU UC-52.
 * SS Scholar (1886) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 90 nmi west south west of the Bishop Rock (48.88333°N, -8.06667°W) by SMU U-55 with the loss of two crew.
 * Tewfig el Bari (🇫🇷 France): World War I: The sailing vessel was sunk in the Mediterranean Sea by SMU UB-51.
 * USS William Rockefeller (1916) : World War I: The tanker was sunk in the North Sea off Kinnaird Head, Aberdeenshire, United Kingdom (57.73333°N, -1.38333°W) by SMU UC-58 with the loss of three of her crew.

19 May

 * Forsøk (🇳🇴 Norway): World War I: The trawler was sunk in the Barents Sea south west of Cape Kanin Nos Russia by SMU U-22 (Germany) . Her crew survived.
 *  Kirstin Jensen (🇩🇰 Denmark): World War I: The schooner was shelled and sunk in the Mediterranean Sea 40 nmi off Cape Palos, Murcia, Spain by SMU UB-50 . Her crew survived.
 * SS Snowdon (1896) ( undefined): World War I: The collier was torpedoed and sunk in the Mediterranean Sea 84 nmi south of Malta by SMU U-63 (Germany) with the loss of two crew.
 *  Water Witch ( undefined): The schooner ran aground in the Strait of Gibraltar and sank.

20 May

 * Agios Dionysios (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (36.65°N, 22.3°W) by SMU U-32 (Austria-Hungary) . Her crew survived.
 * Angeliki (🇬🇷 Greece): World War I: The sailing vessel was sunk in the Mediterranean Sea (36.65°N, 22.3°W) by SMU U-32 (Austria-Hungary) . Her crew survived.
 *  Khariton Leptev (Flag of Russian SFSR.svg Russia): World War I: The auxiliary brigantine was sunk in the Barents Sea off Murmansk by SMU U-22 (Germany).
 * SS New Sweden (1913) (🇸🇪 Sweden): World War I: Convoy GaG 24: The cargo ship was sunk in the Mediterranean Sea 20 nmi off the Sabinal Lighthouse, Spain (36.4°N, -2.66667°W) by SMU UB-50 . Her crew survived.

21 May

 * SS Chatham (1904) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 80 nmi south west of Cape Matapan, Greece (34.85°N, 21.56667°W) by SMU U-32 (Austria-Hungary) . Her crew survived.

22 May

 * Meran (🇳🇴 Norway): World War I: The sailing vessel was sunk in the North Sea off Songvår, Vest-Agder by SMU U-86 . Her crew survived.
 * SS Red Rose (1891) ( undefined): World War I: The coaster was sunk in the English Channel approximately 30 nmi north of Cap d'Antifer, Seine-Maritime, France (50.06667°N, -0.33333°W) by SMU UB-57 with the loss of eleven of her crew.

23 May

 * SS Innisfallen (1896) ( undefined): World War I: The passenger ship was torpedoed and sunk in the Irish Sea 16 nmi east by north of the Kish Lightship ( undefined) (53.43333°N, -5.35°W) by SMU UB-64 with the loss of ten lives.
 * SS Mefjord (1914) (🇳🇴 Norway): World War I: The coaster was torpedoed and sunk in the Atlantic Ocean off Trevose Head, Cornwall, United Kingdom (50.46667°N, -5.18333°W) by SMU UC-64 . Her crew survived.
 * HMS Moldavia : World War I: The armed merchant cruiser, operating as a troopship, was torpedoed and sunk in the English Channel off Beachy Head, East Sussex (50.4°N, -0.43333°W) by SMU UB-57 with the loss of 56 lives.
 * SS Skaraas (1882) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 1 nmi off Black Head, Cornwall (49.98333°N, -5.1°W) by SMU UB-74 with the loss of nineteen of her crew.
 * SMU UB-52 : World War I: The Type UB III submarine was torpedoed and sunk in the Strait of Otranto (41.6°N, 18.86667°W) by HMS H4 with the loss of 32 of her 34 crew.

24 May

 * HMT Gabir : World War I: The naval trawler struck a mine and sank in the North Sea of Pakefield, Suffolk with the loss of two of her crew.
 *  Ruth Hickman ( undefined): World War I: The schooner was scuttled in the Atlantic Ocean 60 nmi north north west of Graciosa, Azores, Portugal (40.08333°N, -28.5°W) by SMU U-62 . Her crew survived.
 * HMT Yucca : World War I: The naval trawler struck a min and sank in the North Sea off Pakefield (52.43333°N, 1.8°W with the loss of seven of her crew. by SMU UC-17 . Her crew survived.

25 May

 * Amiral Lafont (🇫🇷 France): World War I: The auxiliary sailing vessel was sunk in the Mediterranean Sea north of the Isla de Alborán, Spain (36.51667°N, -2.45°W) by SMU UB-50.
 *  Hattie Dunn (🇺🇸 United States): World War I: The three-masted schooner was scuttled in the Atlantic Ocean (37.66667°N, -74.96667°W) by SMU U-151 . Her crew survived.
 * Santa Teresa ( undefined): World War I: The sailing vessel was scuttled in the Mediterranea Sea north of the Isla de Alborán (36.5°N, -2.71667°W) by SMU UB-50.
 * SS Saphir (1901) (🇳🇴 Norway): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 1.5 nmi north north west of Trevose Head, Cornwall, United Kingdom by SMU U-94 . Her crew survived.

26 May

 * HMT Clara & Alice : The naval trawler was lost on this date.
 * Dayspring ( undefined): World War I: The fishing smack was shelled andsunk in the North Sea off the coast of Norfolk by SMU UB-40 . Her crew survived.
 * Eclipse ( undefined): World War I: The fishing smack was shelled and sunk in the North Sea off the coast of Norfolk by SMU UB-40 . Her crew survived.
 * Fortuna ( undefined): World War I: The fishing smack was scuttled in the North Sea off the coast of Norfolk by SMU UB-40 . Her crew survived.
 * SS Janvold (🇳🇴 Norway): World War I: The cargo ship was sunk in the Irish Sea 28 nmi north west of Bardsey Island, Pembrokeshire by SMU U-98 with the loss of four crew.
 * SS Kyarra (1903) ( undefined): World War I: The passenger ship was sunk in the English Channel 2 nmi south south east of Anvil Point, Dorset by SMU UB-57 with the loss of six of her crew.
 * SS Le Gard (1890) (🇫🇷 France): World War I: The passenger ship was torpedoed and sunk in the Mediterranean Sea 88 nmi north west of Cape Bengut, Algeria by SMU UB-49 with the loss of fourteen lives.
 * SS Princess Royal (1912) ( undefined): World War I: The passenger ship was torpedoed and sunk in the Atlantic Ocean 3 nmi west north west of St. Agnes, Cornwall (50.32333°N, -5.33167°W) by SMU U-101 with the loss of nineteen crew.
 * SS Thames (1887) ( undefined): World War I: The cargo ship was torpedoed and sunk in the North Sea 6 nmi south east by east of Seaham, County Durham by SMU UC-17 with the loss of four of her crew.
 * SMU UB-74 : World War I: The Type UB III submarine was depth charged and sunk in Lyme Bay (50.53333°N, -2.53333°W) by HMY Lorna with the loss of all 35 crew.

27 May

 *  Carmela ( undefined): World War I: The brigantine was sunk in the Mediterranean Sea 80 nmi south east of Formentera, Spain by SMU UB-49.
 * Carskey ( undefined): The ketch sprang a leak and foundered. Her crew were rescued.
 * SS Forto (🇳🇴 Norway): The cargo ship collided with another vessel and sank. Her crew were rescued.
 * Joseph Simone (🇫🇷 France): World War I: The fishing vessel was sunk in the English Channel north west of Fécamp, Seine-Maritime by SMU UB-57.
 * SS Leasowe Castle (1915) ( undefined): World War I: The troopship was torpedoed and sunk in the Mediterranean Sea 104 nmi west by north of Alexandria, Egypt (31.5°N, 27.93333°W) by SMU UB-51 with the loss of 101 lives.
 * SS Merionethshire (1913) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 120 nmi north of the Azores, Portugal by SMU U-62 . Her crew survived.
 * SS Molière (1882) (🇫🇷 France): World War I: The cargo ship was sunk in the Atlantic Ocean 1 nmi off Hartland Point, Devon, United Kingdom by SMU U-101 with the loss of twelve crew.
 * Petit Georges (🇫🇷 France): World War I: the fishing vessel was sunk in the English Channel north west of Fécamp (49.88333°N, 0.25°W) by SMU UB-57.
 * Souvenir de Ste Marie (🇫🇷 France): World War I: The fishing vessel was sunk in the English Channel north west of Fècamp by SMU UB-57.
 * SS Uganda (1898) ( undefined): World War I: Convoy GaG28: The cargo liner was torpedoed and damaged in the Mediterranean Sea 90 nmi north east of Algiers, Algeria (38.26667°N, 3.5°W) by SMU UB-49 . She sank on 29 May 40 nmi north east of Algiers. Her crew survived.
 * Wayside Flower ( undefined): World War I: The vessel was scuttled in the North Sea 20 nmi north east by north of the mouth of the Humber by SMU UC-70.

28 May

 * SS Cairnross (1913) ( undefined) : World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 110 nmi west north west of Flores Island, Azores by SMU U-62 . Her crew survived.
 * Coronation ( undefined): World War I: The fishing vessel was scuttled in the North Sea 13 nmi east south east of Flamborough Head, Yorkshire by SMU UC-70 (.
 * MV Dronning Margrethe (1892) (🇩🇰 Denmark): World War I: The coaster was sunk in the North Sea 140 km east of Dundee, Forfarshire, United Kingdom (56.5°N, 1.9°W) by SMU U-111 . Her crew survived.
 * Flora (🇫🇷 France): World War I: The sailing vessel was scuttled in the Atlantic Ocean 2 nmi off Tintagel, Cornwall, United Kingdom (50.76667°N, -4.68333°W) by SMU U-101.

29 May

 * SS Begum (1907) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 270 nmi west by south of the Bishop Rock, Isles of Scilly (47.5°N, -12.46667°W) by SMU U-90 with the loss of fifteen of her crew.
 * SS Carlton (1905) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Atlantic Ocean 270 nmi west by south of the Bishop Rock by SMU U-90 . Her crew survived.
 * HMT Dirk : World War I, The coaster, operating as a naval trawler, was torpedoed and sunk in the North Sea off Flamborough Head, Yorkshire (54.13333°N, 0.18333°W) by SMU UC-75 with the loss of twenty of her crew.
 * SS Missir (1864) ( undefined): World War I: The coaster was torpedoed and sunk in the Mediterranean Sea 80 nmi west by north of Alexandria, Egypt by SMU UB-51 with the loss of 34 crew.
 *  Souvenir (🇩🇰 Denmark): World War I: The barque was shelled and sunk in the Atlantic Ocean (51.78333°N, -7.76667°W) by SMU U-101 . Her crew survived.

30 May

 * SS Asiatic Prince (1910) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 190 nmi east by south of Malta by SMU U-63 (Germany) . Her crew survived.
 * SS Ausonia (1909) ( undefined): World War I: The passenger ship was torpedoed and sunk in the Atlantic Ocean 620 nmi west south west of the Fastnet Rock (47.98333°N, -23.7°W) by SMU U-62 with the loss of 44 crew.
 * SS Aymeric (1905) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea 145 nmi souht west by west of Cape Matapan, Greece (34.88333°N, 20.25°W) by SMU U-63 (Germany) . Her crew survived.
 * Cyprus (🇮🇲 Isle of Man): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Glad Tidings (🇮🇲 Isle of Man): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Honey Bee ( undefined): World War I: The fishing vessel was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Jane Gordon ( undefined): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Lloyd (🇮🇲 Isle of Man): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Marianne McCrum ( undefined): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Never Can Tell ( undefined): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * SS Pietro Maroncelli (1896) ( undefined): World War I: The cargo ship was torpedoed and sunk in the Mediterranean Sea west of Sardinia (40.8°N, 8°W) by SMU UB-49 . Her crew survived.
 * Seabird ( undefined): World War I: The fishing vessel was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * Sparkling Wave ( undefined): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * St. Mary ( undefined): World War I: The fishing smack was scuttled in the Irish Sea 26 nmi west north west of the Calf of Man by SMU UB-64 . Her crew survived.
 * SS Waneta (1910) ( undefined): World War I: The tanker was torpedoed and sunk in the Atlantic Ocean 42 nmi south south east of the Old Head of Kinsale, County Cork by SMU U-101 with the loss of eight crew.

31 May

 * Alert ( undefined): World War I: The sailing vessel was scuttled in the North Sea 6 nmi north east of Boulmer, Northumberland by SMU UB-40.
 *  Attila ( undefined): The brig caught fire at Itaporã, Brazil. She was beached but was a total loss.
 * HMS Fairy (1897) : World War I: The Gipsy-class destroyer foundered in the North Sea off Flamborough Head, Yorkshire after ramming and sinking SMU UC-75.
 * USS President Lincoln (1907) : World War I: The troopship was torpedoed and sunk in the Atlantic Ocean 600 nmi off Brest, Finistère, France by SMU U-90 with the loss of 26 of the 715 people on board. Survivors were rescued by USS Smith (DD-17) and USS Warrington (DD-30) (both ).
 * Pretty Polly ( undefined): World War I: The fishing smack was shelled and sunk in the Atlantic Ocean off the coast of County Galway, Ireland by SMU U-101 with the loss of seven crew.
 * SMU UC-75 : World War I: The Type UC II submarine was rammed and sunk in the North Sea off Flamborough Head by SS Blaydonian ( undefined and HMS Fairy (1897).

Unknown date

 * HNLMS Frans Naerebont : The minesweeper struck a mine and sank in the North Sea off Terschelling, Friesland in early May with the loss of at least five of her nineteen crew.