German submarine U-253 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine during World War II.
The U-boat was laid down 15 November 1940 at the Bremer Vulkan shipyard in Bremen-Vegesack, launched on 30 August 1941 and commissioned on 21 October 1941. U-253 served with the 8th U-boat Flotilla for training before being assigned operationally to the 6th U-boat Flotilla from 1 to 25 September 1942. She completed one patrol but did not sink any ships.
U-253 was sunk with all hands on 25 September 1942 in the Denmark Strait, northwest of Iceland, at . The exact cause of her loss is uncertain, but it is believed to have been a British mine in the Northern Barrage.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-253 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 AEG GU 460/8-276 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-253 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.