German submarine U-674 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 7 April 1942 at the Howaldtswerke yard at Hamburg, launched on 8 May 1943, and commissioned on 15 June 1943 under the command of Oberleutnant zur See Harald Muhs.
Attached to 5th U-boat Flotilla based at Kiel, U-674 completed her training period on 31 January 1944 and was assigned to front-line service.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-674 had a displacement of when at the surface and while submerged. She had a total length of , a pressure hull length of , a beam of , a height of , and a draught of . The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of for use while surfaced, two Siemens-Schuckert GU 343/38âÂÂ8 double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-674 was fitted with five torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one SK C/35 naval gun, 220 rounds, and two twin C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
While operating against convoy RA 59, U-674 was detected by Swordfish B of 842 Naval Air Squadron embarked on , an escort carrier, north of Tromsø on 2 May 1944. The aircraft attacked, destroying the U-boat. All 49 crew members perished in the attack.