HMS Sea Nymph was a S-class submarine of the third batch built for the Royal Navy during World War II.

Completed in July 1942, she spent the majority of her career patrolling the waters off Norway in the North Sea, then was sent to the Pacific but was forced back due to technical problems.

The submarine then participated in Operation Source, an attempt to sink German battleships in Norway threatening allied Arctic convoys.

In March 1944, Sea Nymph was sent to the United States for a refit; she returned in October, then after an uneventful patrol, she had her battery changed.

She had to turn back and have her battery replaced again after encountering problems; after arriving in the Philippines, on 13 July Sea Nymph caught on fire and was damaged beyond the repair capabilities of local shipyards.

[6] On 1 November 1942, P 73, under the command of Lieutenant Geoffrey D. N. Milner, sailed to Holy Loch, where she was commissioned two days later as HMS Sea Nymph.

[8] After going through training exercises off Scapa Flow and Holy Loch, Sea Nymph set sail on 16 December 1942 for an anti-submarine patrol off Norway.

[7] After torpedo and gunnery exercises of the River Clyde area, the boat commenced another patrol in the Bay of Biscay, west of France on 28 June.

[10][7] After an uneventful patrol in the Arctic from 15 November to 7 December 1943, Sea Nymph was ordered to transport British agents and equipment from Shetland to off Norway, where they would be transferred to a local fishing vessel.

[7] On 25 March 1944, Sea Nymph departed Great Britain for the US, where she was due to refit at the Philadelphia Naval Shipyard.

On 11 October, she returned to Holy Loch and underwent additional training, then the submarine went on another patrol from 6 to 17 January 1945 in the Norwegian Sea in search of German U-boats.

After having her battery changed during February in Elderslie, Scotland, Sea Nymph was reassigned to the Pacific theater of operations, arriving at Gibraltar on 22 March.

After temporary repairs allowing her to get underway, she departed Subic Bay and made the trip back to Great Britain, arriving on 30 October 1945.