October 21, 1942 – Finnish submarine Vesihiisi sank Soviet submarine S-7 southwest of Aland Islands, Finland with one torpedo at 2041 hours; 44 were killed, 4 survived. Vesihiisi was a Finnish 500-tonne Vetehinen class submarine that was constructed in the early 1930s. The vessel served in the Finnish Navy during the second World War. In the evening of 21 October 1942 she torpedoed and sank the Soviet S class submarine S-7, near Lågskär in the Sea of Åland. The captain (Sergei Lisin) and four of the crew of the S-7 were then captured.