German submarine U-704

German submarine U-704 was a Type VIIC U-boat of the German Kriegsmarine during World War II.

Commissioned on 18 November 1941 under the command of Kapitänleutnant Horst Kessler, U-704 carried out training operations as part of the 8th U-boat Flotilla until June 1942. U-704 set out on its first patrol, a transit to its operational base at Saint-Nazaire on 30 June 1942. During this patrol, U-704 formed part of wolfpack "Wolf" which was to patrol between Iceland and Greenland, out of the range of allied air cover. On 26 July 1942, U-704 torpedoed the British freighter Empire Rainbow, part of convoy Convoy ON-113. Empire Rainbow had already been damaged by a torpedo from U-607, and U-704's torpedo sank the freighter.

U-704 carried out a further four operational patrols under the command of Kessler from Saint Nazaire and La Pallice, sinking no further ships. U-704 did fire four torpedoes at the troopship Queen Elizabeth on 9 November 1942, with Kessler claiming a hit, although Queen Elizabeth was undamaged.

U-704 then served as a training submarine in the Baltic sea for the rest of the war, and was scuttled at Vegesack on 4 May 1945.