HMS Sunfish was a Royal Navy S-class submarine which was launched on 30 September 1936 and served in the Second World War.

At the onset of the Second World War, Sunfish was a member of the 2nd Submarine Flotilla.

From 26–29 August 1939, the flotilla deployed to its war bases at Dundee and Blyth.

In February 1940, she attacked the German U-boat U-14, but missed, and in April sank two German merchant ships, Amasis and Antares, and narrowly missed Hanau and an auxiliary patrol vessel.

2nd rank Fisanovich – had allegedly taken her out of her assigned area and she was diving when the aircraft came in sight instead of staying on the surface and firing recognition signals as instructed.