German submarine U-646

German submarine U-646 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 23 December 1941 at the Blohm & Voss yard at Hamburg, launched on 3 September 1942, and commissioned on 29 October 1942 under the command of Leutnant zur See d.R. Heinrich Wulff.

Attached to 5th U-boat Flotilla based at Kiel, U-646 completed her training period on 31 March 1943 and was assigned to front-line service.

Service history
While on patrol in the North Atlantic, U-646 was detected by Hudson J of No. 269 Squadron RAF south-east of Iceland on 17 May 1943. In the subsequent attack, the U-boat was sunk and all 46 crew members perished.