German submarine U-15 was a Type IIB U-boat of the Kriegsmarine. It was commissioned on 7 March 1936, following construction at the Deutsche Werke shipyards at Kiel. Its first commander was Werner von Schmidt. In its career, it completed five patrols, all while serving under the 1st U-boat Flotilla. It sank three ships.
German Type IIB submarines were enlarged versions of the original Type IIs. U-15 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-15 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.
On 30 January 1940, U-15 was sunk in the North Sea in the Hoofden, after being rammed by accident by the German torpedo boat Iltis. 25 men died; there were no survivors.