The Rocket U-boat was a series of military projects undertaken by Nazi Germany during the Second World War. The projects, which were undertaken at Peenemünde Army Research Center, aimed to develop submarine-launched rockets, flying bombs and missiles. The Kriegsmarine (German Navy) did not use submarine-launched rockets or missiles from U-boats against targets at sea or ashore. These projects never reached combat readiness before the war ended.
From May 31 to June 5, 1942, a series of underwater-launching experiments of solid-fuel rockets were carried out using submarine U-511 as a launching platform.