S-2 was the second S-class submarine of the Soviet Navy. In early 1940, it entered Swedish territorial waters in the Sea of Åland where it hit a Swedish naval mine, and sank on January 2, 1940, with the loss of all 50 crew members.
The Srednyaya or S-class submarine (Russian: Средняя|lit=medium), also called the Stalinets-class (Russian: Сталинец|lit=follower of Stalin), was an ocean-going diesel electric attack submarine. Its pressure hull had seven compartments, and the Series IX submarine's displacement was 840t while on the surface and 1070t while submerged. It had a length of 77.8m (255.2feet), a beam of 6.4m (21feet), and a draft of 4m (13feet). It had two diesel engines to power it on the surface and two electric motors for when it was submerged, providing and, respectively, to the two propeller shafts. This gave it a speed of 19.5kn on the surface and 9kn while underwater, and the submarine had a range of 9500nmi. Its test depth was 80m (260feet), and as armament it had six 530NaN torpedo tubes, one 100mm deck gun, and one 45mm gun.[1]
S-2 was one of three Series IX boats, along with and . The original design was made by German engineers at NV Ingenieurskantoor voor Scheepsbouw, the Dutch subsidiary of AG Weser, and later boats were modified by the Soviets to take into account the manufacturing capabilities available in the Soviet Union. After examining the German prototype submarine E-1 in 1932 and 1933, Soviet engineers decided to purchase its design for the Soviet Navy with some changes, increasing its size, range, and armament. E-1 became the basis for the first three S-class submarines, the Series IX boats, which were built in Leningrad using some German components.
A search for the submarine wreck was begun in April 1999[2] by a team of divers from Sweden and Åland. According to the Military Archives of Sweden, the submarine hit the mine in Swedish territorial waters, but the Finnish archives specify the sinking occurred on Finnish territorial waters. The uncertainty of position necessitated a prolonged search. The diving team finally discovered the wreck inside Swedish territorial waters. One member of the diving team, Ingvald Eckerman, is a grandson of J. A. Eckerman who, as the lighthouse-keeper of the lighthouse at Märket, witnessed the submarine sinking in 1940.[3]
The wreck was emptied of munitions during the summer of 2012.[4]