
The Type II U-boat was designed by Nazi Germany as a coastal U-boat, modeled after the CV-707 submarine, which was designed by the Dutch dummy company NV Ingenieurskantoor voor Scheepsbouw Den Haag (I.v.S) and built in 1933 by the Finnish Crichton-Vulcan shipyard in Turku, Finland. It was too small to undertake sustained operations far away from the home support facilities. Its primary role was found to be in the training schools, preparing new German naval officers for command. It appeared in four sub-types.

German submarine U-1 was the first U-boat built for Nazi Germany's Kriegsmarine following Adolf Hitler's abrogation of the terms of the Treaty of Versailles in 1935, which banned Germany possessing a submarine force.
German submarine U-2 was a Type IIA U-boat of Nazi Germany's Kriegsmarine. Her keel was laid down 11 February 1935 by Deutsche Werke of Kiel as yard number 237; she was launched on 1 July and commissioned on 25 July 1935 with Oberleutnant zur See (Oblt.z.S.) Hermann Michahelles in command.

German submarine U-3 was a Type IIA U-boat laid down at the Deutsche Werke in Kiel on 11 February 1935 as yard number 238. She was commissioned into the Kriegsmarine on 6 August 1936 under the command of Oberleutnant zur See (Oblt.z.S.) Hans Meckel.

German submarine U-4 was a Type IIA U-boat of Nazi Germany's Kriegsmarine before and during World War II. She was one of the longest lasting German submarines of the period, primarily since half of her time was spent on training duties in the Baltic Sea.

German submarine U-5 was a Type IIA U-boat of Nazi Germany's Kriegsmarine. She was laid down on 11 February 1935, launched on 14 August and commissioned 31 August that year, under Oberleutnant zur See Rolf Dau.

The German submarine U-6 was a long-lived but very inactive Type IIA U-boat built before World War II for service in Nazi Germany's Kriegsmarine.

German submarine U-7 was a Type IIB U-boat of Nazi Germany's Kriegsmarine, based out of Kiel during World War II. It was one of the smaller versions, and was first launched on 29 June 1935 with a crew of 29. Its first commander was Kurt Freiwald. U-7 would have 16 commanders over the course of its service, the last being Günther Loeschcke.

The German submarine U-8 was a Type IIB U-boat of Nazi Germany's Kriegsmarine, based at Kiel during World War II. It was one of the smaller versions, and was first launched on 16 July 1935. Its first commander was Harald Grosse. U-8 would have 18 commanders over the course of its service, the last being Jürgen Kriegshammer.

German submarine U-9 was a Type IIB U-boat of Nazi Germany's Kriegsmarine. Her keel was laid down on 8 February 1935, by Germaniawerft in Kiel as yard number 543. She was launched on 30 July 1935 and commissioned on 21 August, with Korvettenkapitän Hans-Günther Looff in command.

German submarine U-10 was a Type IIB U-boat built before World War II for service in Nazi Germany's Kriegsmarine. As she was one of the first batch of boats built following the renunciation of the Treaty of Versailles, she was only capable of coastal and short cruising work. This led to her being reassigned to training duties after the Norwegian campaign of 1940 together with many of her sister boats.

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.

German submarine U-12 was a Type IIB U-boat of Nazi Germany's Kriegsmarine laid down on 20 May 1935 by Germaniawerft at Kiel and commissioned on 30 September.

German submarine U-13 was a Type IIB U-boat of Nazi Germany's Kriegsmarine which was commissioned on 30 November 1936, following construction at the Deutsche Werke shipyards at Kiel. The first commander on board was Hans-Gerrit von Stockhausen. In her career she completed nine patrols, all while serving with the 1st U-boat Flotilla. The U-boat succeeded in sinking nine ships and damaging three more.

German submarine U-14 was a Type IIB U-boat of Nazi Germany's Kriegsmarine during World War II. It served with 3rd U-boat Flotilla from 18 January 1936 to 31 October 1939. U-14 completed six wartime patrols and sank nine ships totalling 12,344 GRT.

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 submarine U-17 was a Type IIB U-boat of Nazi Germany's Kriegsmarine. It was built in Germaniawerft, Kiel, where it was laid down on 1 July 1935 and commissioned on 3 December 1935, under the command of Werner Fresdorf.

German submarine U-18 was a Type IIB U-boat of Nazi Germany's Kriegsmarine during World War II. It was laid down 10 July 1935 and commissioned on 4 January 1936. It served in many U-boat flotillas during its service.

German submarine U-19 was a Type IIB U-boat of Nazi Germany's Kriegsmarine during World War II. Her keel was laid down on 20 July 1935, at the Germaniawerft of Kiel. She was launched on 21 December 1935, and commissioned on 16 January 1936, under the command of Kapitänleutnant Viktor Schütze.

German submarine U-20 was a Type IIB U-boat of Nazi Germany's Kriegsmarine. Her keel was laid down on 1 August 1935, by Germaniawerft of Kiel as yard number 550. She was commissioned on 1 February 1936. During World War II, she conducted operations against enemy shipping.

German submarine U-21 was a Type IIB U-boat of Nazi Germany's Kriegsmarine. Her keel was laid down 4 March 1936, by Germaniawerft of Kiel as yard number 551. She was commissioned on 3 August 1936. During World War II, she conducted operations against enemy shipping.

German submarine U-22 was a Nazi German Type IIB U-boat which was commissioned in 1936 following construction at the Germaniawerft shipyards at Kiel. Her pre-war service was uneventful, as she trained crews and officers in the rapidly expanding U-boat arm of the Kriegsmarine following the abandonment of the terms of the Treaty of Versailles two years before.

German submarine U-23 was a Type IIB U-boat of Nazi Germany's Kriegsmarine, built in Germaniawerft, Kiel. She was laid down on 11 April 1936 and commissioned on 24 September.

German submarine U-24 was a Type IIB U-boat that was in service of Nazi Germany's Kriegsmarine during World War II. She was laid down on 21 April 1936 at the F. Krupp Germaniawerft in Kiel with yard number 554, launched on 24 September and commissioned into the Kriegsmarine on 10 October. Oberleutnant zur See Heinz Buchholz took command on 3 July 1937.

German submarine U-120 was a Type IIB U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down on 31 March 1938 at the Flender Werke, Lübeck as yard number 268. She was launched on 16 March 1940 and commissioned on 20 April under Oberleutnant zur See (Oblt.z.S.) Ernst Bauer.

German submarine U-121 was a long-lived Type IIB U-boat built during World War II for service in Nazi Germany's Kriegsmarine. U-121 spent the entire war as a training vessel and was scuttled at the end of the conflict.