Louhi was sunk on 12 January 1945 after a mine laying operation in the Lapland War, in an area south of Hanko. Louhi had been laying mines together with Ruotsinsalmi, in order to prevent German Navy operations in the area. The Finnish vessels were escorted by pair of Soviet MO-boats when a large explosion wracked the stern of Louhi. The vessel sank in two minutes, taking 10 men into the depth of 40 meters, while escorting Soviet ships saved the surviving crew from the freezing sea. The sinking took place 7.5 nautical miles to the south-east of the Russarö lighthouse.
