German submarine U-1020 was a Type VIIC/41 U-boat of Nazi Germany's Kriegsmarine during World War II.
She was ordered on 13 June 1942, and was laid down on 30 April 1943, at Blohm & Voss, Hamburg, as yard number 220. She was launched on 22 March 1944, and commissioned under the command of Oberleutnant zur See Otto Eberlein on 17 May 1944.
German Type VIIC/41 submarines were preceded by the heavier Type VIIC submarines. U-1020 had a displacement of when at the surface and while submerged. She had a total length of , a pressure hull length of , an overall 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 BBC 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-1020 was fitted with five torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes or 26 TMA or TMB Naval mines, one SK C/35 naval gun, 220 rounds, one Flak M42 and two C/30 anti-aircraft guns. The boat had a complement of between forty-four and fifty-two.
U-1020 had a Schnorchel underwater-breathing apparatus fitted out sometime before June 1944.
On 22 November 1944, U-1020 left Horten on her first, and only, war patrol. Forty-nine days into her patrol, 9 January 1945, U-1020 struck a British mine east of Dundee in the North Sea. All 52 of her crew went down with the boat.
The wreck now lies at .