U-721
A training boat that never entered operational service but that, with other training and advanced-model submarines that never saw action, played a role in evacuating German civilians as the Red Army entered Germany. In late February 1945, U-721, by using every inch of available space on board, successfully evacuated about 100 civilian refugees and wounded soldiers from the port of Hela (now Hel, Poland).

Type: VII C
Built: H.C. Stülcken & Sohn, Hamburg
Keel laid: 16 November 1942
Launched: 23 July 1943
Commissioned: 8 November 1943
Commanders:
OL Otto Wollschläger, November 1943-December 1944
OL Ludwig Fabricius, December 1944-May 1945
Fate: Scuttled by her own crew 5 May 1945.