Ruotsinsalmi and her sister vessel, Riilahti, were intended as escort minesweepers for the Finnish navy's coastal defence ships Ilmarinen and Väinämöinen, and they were therefore designed with a draught of only 1.5 metres (4 ft 11 in).

Ruotsinsalmi and Riilahti began mining the Gulf of Finland on 26 June 1941, immediately after the outbreak of the Continuation War.

The voyage back through the minebarrier with a convoy of freighters started at midnight of 3 December after the escort group had been strengthened with German minesweepers M 4 and M 7 and it took place without any incidents.

[4] Ruotsinsalmi was Finland's most active minelayer during the Second World War, laying a total of 3,967 sea mines and 541 sweeping obstacles.

She was mothballed in Upinniemi, and there were plans to make her into a museum, but she was scrapped at the beginning of the 1990s, after the owners had failed to gather enough funds.