Delphin

The Delphin (dolphin) was a midget submarine created during World War II. Designed in 1944, only three prototypes were created by Nazi Germany's Kriegsmarine by the end of the war, all of which were destroyed. The Delphin was built for underwater speed attacks, as German engineers under the leadership of Ulrich Gabler discovered that past midget submarines were too slow to match the speeds of large ships in the English Channel.