German submarine U-70 was a Type VIIC submarine of Nazi Germany's Kriegsmarine during World War II.
The U-boat was laid down on 19 December 1939 at the Friedrich Krupp Germaniawerft shipyard at Kiel as yard number 604, launched on 12 October 1940, and commissioned on 23 November under the command of Kapitänleutnant Joachim Matz to serve with the 7th U-boat Flotilla from 23 November 1940 until she was sunk by British warships south of Iceland on 7 March 1941.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-70 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-70 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 one C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
U-70s first and only patrol began on 20 February 1941. On 26 February she sank the 820 GRT Swedish merchant ship Göteborg, south of Iceland.
U-70 joined , , and in a wolfpack that attacked Convoy OB 293 south-east of Iceland on 7 March 1941. In her first attack at 04:45, U-70 damaged the 6,568 GRT British tanker Athelbeach (later sunk by U-99), and the 6,423 GRT British merchant vessel Delilian.
At 07:25 U-70 struck again and hit the 7,493 GRT Dutch tanker Mijdrecht. However the master spotted the periscope of U-70, rammed the submerged U-boat at , damaging the conning tower, and reported its position to the convoy escorts.
At 08:15, the British corvette sighted U-70, which promptly dived. Until 10:30 Camellia and her sister ship attacked five times with depth charges, then Arbutus made another four attacks. In total the two corvettes dropped 48 depth charges. Finally, at 12:44, U-70 was forced to the surface and was abandoned by her crew at . Twenty-five survivors of her crew of forty-five were picked up and taken prisoner.