Tradewind was a T-class submarine of the third group, pennant P329. The name is the trade wind. Chatham Dockyard laid her down on 11 February 1942. She was launched on 11 December 1942 as P329 and renamed Tradewind in March 1943, before she was finished. She is the only Royal Navy ship of this name.
Lieutenant Commander Stephen Lynch Conway Maydon had her for trials off Sheerness in September 1943. One list dates the commissioning 16 September 1943. The completion date used here is 18 October 1943. She worked up in the Clyde. In February 1944 she escorted the damaged submarine Stubborn. She then went out to the Eastern Fleet and joined the 4th Submarine Flotilla at Trincomalee in April 1944.
On 16 September 1944, south of Padang, she sank two small Japanese vessels. Two days later, on the afternoon of 18 September, off the west coast of Sumatra, she sighted the cargo ship Junyo Maru. She had no way to know the cargo was prisoners and Javanese forced laborers. At about 1,800 yards she fired four torpedoes. Two hit. An escort dropped depth charges and she went deep. Junyo Maru sank by the stern in about 15 minutes. The dead are put at more than 5,000. The counts are not agreed.
On 30 October 1944 she laid mines in the Mergui Archipelago. The cargo ship Kyokko Maru sank on 1 January 1945 after hitting one of those mines. On 11 February 1945 she sank the small merchant Nanshin Maru. She is also credited with nine Japanese sailing vessels, two other small craft, and a tug.
Lieutenant J. Nash had her by April 1945. On 28 April 1945, in the Gulf of Siam near 6°48′N, 101°36′E, she torpedoed the tanker Takasago Maru. That tanker is not the hospital ship of the same name. An escort hunted her and did no damage.
She was not sunk. From July 1945 to September 1946 she was altered into an acoustic trials submarine. The external tubes and the guns came off, the bridge was faired, and some of the internal tubes were blanked. On 15 June 1953 she was at the Coronation Fleet Review at Spithead. She was scrapped at Charlestown on 14 December 1955.