German submarine U-521
 German submarine U-521 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II.She was built by the Deutsche Werft yard at Finkenwerder Hamburg with yardnumber 336. Commissioned in June 1942 she was commanded by Kapitänleutnant Klaus Bargsten.The U-boat was assigned to the 4th U-boat Flotilla for training and the 2nd flotilla for operations.U-521 was sunk on 2 July 1943 by the submarine chaser USS Gilmer. The only survivor was Bargsten himself.