HMS Swordfish (61S) was a first-batch S-class submarine built for the Royal Navy during the 1930s. Commissioned in 1932, she was given the pennant number 61S and was assigned to the 2nd Submarine Flotilla. At the start of World War II, Swordfish was missed with three torpedoes by her sister ship after being mistaken for a German U-boat. On 20 April 1940, she attacked a German convoy, but her torpedoes failed to hit their targets. Two days later, she sighted another convoy, but did not attack it because of the ships' shallow draught. In the morning of 26 April, she dived to avoid drifting mines; one of them hit but did not explode. During her sixth war patrol, Swordfish was mistakenly bombed by a British aircraft, but sustained no damage. Swordfish disappeared during her twelfth patrol, after departing Portsmouth on 7 November. Although she was initially thought to have been sunk by German destroyers off Brest, she was determined to have been sunk by a mine when her wreck was discovered by diver Martin Woodward in June 1983 off the Isle of Wight. She had left Portsmouth Harbour only hours before, and it is assumed that she was carrying out a trim dive when she struck the German mine. Design and description The S-class submarines were designed as successors to the L class and were intended to operate in the North and Baltic Seas. The submarines had a length of overall, a beam of and a mean draught of . They displaced on the surface and submerged. The S-class submarines had a crew of 38 officers and ratings. They had a diving depth of . For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the first-batch boats had a range of at and at submerged. The boats were armed with six torpedo tubes in the bow. They carried six reload torpedoes for a grand total of a dozen torpedoes. They were also armed with a deck gun. Construction and career Swordfish was ordered on 2 July 1930 and was laid down by Chatham Dockyard on 1 December that same year. The submarine was launched on 10 November 1931 and commissioned on 28 November 1932. At the onset of World War II, Swordfish