The second HMS Tarpon (N17) was a T-class submarine of the Royal Navy. She was laid down by Scotts, Greenock and launched in October 1939. She is named after the large fish Tarpon; one species of which is native to the Atlantic, and the other to the Indo-Pacific Oceans.

The Royal Navy's T class of diesel-electric submarines was designed in the 1930s to replace the O, P, and R classes. Fifty-three members of the class were built just before and during the Second World War, where they played a major role in the Royal Navy's submarine operations. Four boats in service with the Royal Netherlands Navy were known as the Zwaardvisch class.