SMS S31[a][b] was a 1913 Type Large Torpedo Boat (Großes Torpedoboot ) of the Imperial German Navy.

[2] S31 was launched at Schichau's Elbing shipyard on 20 December 1913 and commissioned on 8 August 1914.

220 tonnes (220 long tons) of fuel oil was carried, giving a range of 1,100 nautical miles (2,000 km; 1,300 mi) at 20 knots (37 km/h; 23 mph).

[2] Armament consisted of three 8.8 cm SK L/45 naval guns in single mounts, together with six 50 cm (19.7 in) torpedo tubes with two fixed single tubes forward and 2 twin mounts aft.

She struck a mine near the island of Ruhnu on 19 August, sinking with the loss of 11 men.