Russarö is an island south of Hanko. The island is closed to the public as it is military area of the Finnish Defence Forces. The island has a five-story stone lighthouse built in 1863 and a Finnish Meteorological Institute weather station.
On 1 December 1939, the Soviet cruiser Kirov accompanied by the destroyers Stremitelnyi and Smetlivyi approached the fortified coastal artillery battery located on the island. After a short exchange of fire Stremitelnyi and Kirov were hit and the detachment retired from battle. 17 men were lost aboard Kirov and 30 were counted wounded.