The second batch of S-class submarines were designed as slightly improved and enlarged versions of the earlier boats of the class and were intended to operate in the North and Baltic Seas.

[2] Ordered on 18 February 1935, Spearfish was laid down on 23 May 1935 in Cammell Laird's shipyard in Birkenhead and was launched on 21 April 1936.

[5] Her wartime career started inauspiciously, when on 24 September 1939, she was heavily damaged by German warships off Horns Reef.

A rescue mission was undertaken by the British Humber force and Home Fleet, including the aircraft carrier HMS Ark Royal, and the battleship HMS Nelson, which performed escort duty whilst search and rescue attempts were made.

The fleet was attacked by Junkers Ju 88 bombers of the Luftwaffe's Kampfgeschwader 30, and a bomb caused slight damage to the battlecruiser HMS Hood.

On 1 August she was spotted on the surface by the German submarine U-34 under the command of Wilhelm Rollmann who attacked and sank her, about 180 miles (290 km) west-southwest of Stavanger.