The Sisu-class motor torpedo boats was a series of two Italian MAS type motor torpedo boats of the Finnish Navy. The vessels were constructed in 1916 by the Orlando shipyard in Livorno, Italy. Sisu and Hurja were purchased by the Finns in 1920, and saw service in World War II. When dashing forward at full speed, the vessels sprayed water high in the air, earning the nickname "the fountains" from Finnish sailors. On 1 October 1941 Sisu, together with Nuoli, was patrolling east of Gogland when it came across a large, stationary Soviet minesweeper of the Fugas-class minesweeper. Sisu missed with her first torpedo, having mistaken the foam painted on the minesweeper's bow for an indication that it was actually moving. A second torpedo hit the minesweeper amidship and sank her.

Vessels of the class