German submarine U-90 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.
She was laid down at the Flender Werke in Lübeck as yard number 294 on 1 October 1940, launched on 25 October 1941 and commissioned on 20 December with Oberleutnant zur See Hans-Jürgen Oldörp in command.
After training with the 8th U-boat Flotilla, U-90 was assigned to the 9th flotilla on 1 July 1942 for operations. She was a member of one wolfpack in a patrol in which she was sunk by a Canadian warship.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-90 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 MAN M 6 V 40/46 four-stroke, six-cylinder supercharged diesel engines producing a total of for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 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-90 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 a C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
Having departed Kiel on 30 June 1942, the boat hugged the southern Norwegian coast before turning west and sailing through the gap separating the Faroe and Shetland Islands. She was attacked and sunk by depth charges from the Canadian destroyer St. Croix in the Northern Atlantic on 24 July, while attacking the convoy ON 113.
U-90 took part in one wolfpack, namely.