German submarine U-757 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. Laid down as yard number 140 at the Kriegsmarinewerft (KMW) in Wilhelmshaven, U-757 served with 6th U-boat Flotilla from 28 February 1942 until 8 January 1944 under the command of Korvettenkapitän Friedrich Deetz.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-757 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 Garbe, Lahmeyer & Co. RP 137/c 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-757 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.
U-757s first victims were the British transport vessel HMS LCT-2398 - destroying 291 tons of shipping - in the convoy HX 228, and the American merchant vessel William C. Gorgas- destroying a further 7,197 GRT of shipping. Both incidents occurred on 11 March 1943, fourteen days into her twenty-five-day-long third patrol. Of the seventy-three crewmen on board the Gorgas, twenty-two perished.
On her fourth patrol, U-757 sank the Norwegian Fernhill on 7 August 1943, thirty-one days into her sixty-day patrol, 4,116 GRT of shipping lost in the sea. Of the ship's forty-four crewmen, forty survived the attack, being rescued by the American tanker Idaho two days later.
On 8 January 1944 in the North Atlantic, south-west of Ireland, U-757 was hit by depth charges from the British frigate and the Canadian corvette . U-757 went down with all 49 seamen, at position .
U-757 took part in five wolfpacks, namely: