German submarine U-657

German submarine U-657 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 5 October 1940 by Howaldtswerke, Hamburg as yard number 806, launched on 12 August 1941 and commissioned on 8 October 1941 under Oberleutnant zur See Hans-Jürgen Radke.

Radke was killed in a fire while the boat was undergoing trials on 14 December 1941.

Service History
The boat's career began with training at 8th U-boat Flotilla on 8 October 1941, followed by active service on 1 March 1942 as part of the 3rd Flotilla in La Pallice, France. Four months later, she transferred to 11th Flotilla, in Bergen, Norway, for the remainder of her service.

In 7 patrols she sank 1 merchant ships, for a total of.

Wolfpacks
U-657 took part in in six wolfpacks, namely
 * Naseweis (31 March 1942 – 10 April 1942)
 * Eisteufel (21 June 1942 – 8 July 1942)
 * Nebelkönig (27 July 1942 – 14 August 1942)
 * Nordwind (24 January 1943 – 4 February 1943)
 * Iller (12 May 1943 – 15 May 1943)
 * Donau 1 (15 May 1943 – 17 May 1943)

Fate
U-657 was sunk on 17 May 1943 in the North Atlantic, E of Cape Farewell, Greenland, in position 58.9°N, -42.55°W, by depth charges from Royal Navy frigate HMS Swale (K217). All hands were lost.