HMS Swordfish 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.
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 61.7 m overall, a beam of 7.3 m and a draught of 3.6 m. They displaced 742t on the surface and 942t when submerged. They carried a crew of 38 officers and ratings and had a diving depth of 91.4 m.
For surface running, Swordfish was powered by two 775 bhp diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 485 kW electric motor. They could reach 13.75 knots on the surface and 10 knots underwater. She was armed with six 21-inch torpedo tubes in the bow. And were also armed with a 3-inch deck gun.
On 1 September 1939, the day the war started, Swordfish departed Dundee for her first war patrol. On 14 September, southeast of Aberdeen, she was mistaken for a U-boat by her sister ship HMS Sturgeon, which fired three torpedoes. Swordfish dived and the torpedoes missed. On 20 April 1940, she attacked a German convoy, but her torpedoes failed to hit their targets. but Swordfish was counterattacked with depth charges until the evening by the convoy's escorts. Two days later, she sighted another convoy of trawlers and escorts but did not attack them due to their shallow draught, which would have caused the torpedoes to run under the convoy. In the morning of 26 April, she dived to avoid drifting mines; one of them hit but did luckily not explode. During her sixth war patrol, Swordfish was mistakenly bombed by a Lockheed Hudson of RAF 224 Sqn, but again sustained no damage. After returning to Blyth, Swordfish conducted another patrol, but only aircraft were sighted. On her eighth patrol, she came across the yacht Maski, enroute to the United Kingdom. After taking in the yacht's crew, Swordfish sank it with gunfire.
HMS Swordfish and her crew of 40 disappeared during her twelfth patrol, relieving HMS Usk which was on patrol off the Western Approaches near Brest. Nothing at all was heard from her after her departure from Portsmouth on 7 November 1940. At the time it was thought that she had been sunk by a German destroyer. However she was discovered in 1983 by a local diver, Martin Woodward, split into two just forward of the gun by a mine. The wreck lies in about 150 feet of water roughly 12 miles south of St. Catherine's Point, Isle of Wight. It is likely that she struck the mine shortly after sailing, whilst carrying out a trim dive. The wreck site is designated as a protected place under the Protection of Military Remains Act 1986.
