German submarine U-921 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. She was ordered on 6 June 1941, and was laid down on 15 October 1941 at Neptun Werft AG, Rostock, as yard number 508. She was launched on 3 April 1943 and commissioned under the command of Oberleutnant zur See Wolfgang Leu on 30 May 1943. Design German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-921 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 SSW GU 343/38-8 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-921 was fitted with five torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes or 26 TMA mines, one SK C/35 naval gun, (220 rounds), one Flak M42 and two twin C/30 anti-aircraft guns. The boat had a complement of between 44 — 52 men. Service history On 24 May 1944, U-921 was spotted off Norway, en route to Narvik, by a Canadian Sunderland, DV990, of 422/R Squadron RCAF piloted by F/O G.E. Holley. U-921 had been searching for which had been attacked from the air earlier in the day and badly damaged. U-921 was able to hit the Sunderland on its attack run causing it to crash into the sea after dropping three depth charges, which resulted in no damage to U-921 but all the crewmen of the Sunderland were lost. Shortly after this first attack U-921 was sighted by another Canadian Sunderland, DW111, of 423/S Squadron RCAF piloted by F/L R.H. Nesbitt. U-921 was able to avoid the five depth charges dropped by the Sunderland but strafing wounded the commander, Oberleutnant zur See Wolfgang Leu, and two other crewmen. As U-921 was diving, Leu was able to get both of the wounded crewmen below,