HMS Starfish was a first-batch S-class submarine (often called the Swordfish class) built for the Royal Navy during the 1930s. Completed in 1933, she participated in the Second World War. During the war, Starfish, part of the 2nd Submarine Flotilla, conducted five uneventful war patrols in the North Sea. On 9 January 1940, during her sixth patrol, she attacked a German minesweeper off Heligoland Bight, but after the attack failed and her diving planes jammed, Starfish was repeatedly attacked with depth charges. Badly damaged, she was forced to surface, and sank after all her crew were rescued by German ships.