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.

[3] For surface running, the boats were powered by two 775-brake-horsepower (578 kW) diesel engines, each driving one propeller shaft.

[2] Ordered on 16 June 1933, Snapper was laid down on 18 September 1933 at HM Dockyard, Chatham and was launched on 25 October 1934.

She was mistakenly attacked by a British aircraft when returning to Harwich after a patrol in the North Sea.

[7] Other sources report that the S-class submarine was depth charged and sunk in the Bay of Biscay south west of Ouessant, Finistère, France (47°25′N 5°47′W / 47.417°N 5.783°W / 47.417; -5.783) by the German minesweepers M-2, M-13 and M-25 with the loss of all 41 crew.