During the war U-7 was responsible for sinking two vessels.
On 18 February 1944, west of Pillau, U-7 sank in what is believed to have been a malfunction during a diving manoeuvre. There were no survivors.
German Type IIB submarines were enlarged versions of the original Type IIs. U-7 had a displacement of 279t when at the surface and 328t while submerged. Officially, the standard tonnage was 2500NaN0, however. The U-boat had a total length of 42.7m (140.1feet), a pressure hull length of 28.2m (92.5feet), a beam of 4.08m (13.39feet), a height of 8.6m (28.2feet), and a draught of 3.9m (12.8feet). The submarine was powered by two MWM RS 127 S four-stroke, six-cylinder diesel engines of 700PS for cruising, two Siemens-Schuckert PG VV 322/36 double-acting electric motors producing a total of 460PS for use while submerged. She had two shafts and two 0.85abbr=onNaNabbr=on propellers. The boat was capable of operating at depths of up to 80-.
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for 35- at ; when surfaced, she could travel at . U-7 was fitted with three 53.30NaN0 torpedo tubes at the bow, five torpedoes or up to twelve Type A torpedo mines, and a 2cm (01inches) anti-aircraft gun. The boat had a complement of twentyfive.
U-7 was ordered on 20 July 1934, i.e. in violation of the Versailles Treaty, which denied Germany possession of submarines. The U-boat was not laid down until 11 March 1935, and launched on 29 June 1935, within weeks of the Anglo-German Naval Agreement, which granted Germany parity with the British Empire in submarines.
Commissioned on 18 July 1935 with Kapitänleutnant Kurt Freiwald in command, U-7 mainly served as a training boat except for two brief deployments during the Invasion of Poland in 1939 and Operation Weserübung in 1940.
On 18 February 1944, west of Pillau, U-7 sank in what is believed to have been a malfunction during a diving manoeuvre. There were no survivors.
| Date | Name | Nationality | Tonnage (GRT) | Fate[1] | |
|---|---|---|---|---|---|
| 22 September 1939 | Akenside |  United Kingdom | 2,694 | Sunk | |
| 29 September 1939 | Takstaas |  Norway | 1,830 | Total loss |