In the 1930s, the Soviet Union built a series of submarines called the S class, based on German designs.

In the summer of 1942, the S7 sank the Swedish cargo ships Margareta and Luleå, delivering iron to Germany. Shortly after, the sub was cruising on the surface at night, off the Swedish coast not far from Norrtälje, when she was spotted by the Finnish submarine Vesihiisi. The Vesihiisi fired one torpedo and the S7 sank quickly.

Four survivors who were standing in the conning tower were rescued by the Finnish sub. They were taken prisoners. Among them was the commander Sergey Lisin.

The official data of war archives alleges that S-7 was torpedoed in Finnish waters, but in July 1998, the S7 was located with side scan sonar at 40-45 m depth off Söderarm in the Stockholm archipelago. The 78 m long submarine is relatively intact except for the stern, where the torpedo hit.