German submarine U-11 was a Type IIB U-boat built before World War II for service in Nazi Germany's Kriegsmarine. She was commissioned on 21 September 1935, with Kapitänleutnant Hans-Rudolf Rösing in command. She served in several training flotillas in her 10-year career, but sank or damaged no ships.
In 1940, U-11 was the first unit to carry out sea trials of a new anechoic tile, which was developed by the Kriegsmarine for reducing a submarines' acoustic signature. This development project was codenamed Alberich after the invisible sorcerer from Germanic mythology.
German Type IIB submarines were enlarged versions of the original Type IIs. U-11 had a displacement of when at the surface and while submerged. Officially, the standard tonnage was , however. The U-boat 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 MWM RS 127 S four-stroke, six-cylinder diesel engines of for cruising, two Siemens-Schuckert PG VV 322/36 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-11 was fitted with three torpedo tubes at the bow, five torpedoes or up to twelve Type A torpedo mines, and a anti-aircraft gun. The boat had a complement of twentyfive.
The U-boat was scuttled on 3 May 1945 in Kiel. The wreck was broken up.