Russarö lies about seven kilometres south of Hanko and is the most accessible of the offshore islands now that the military has left. The 1863 lighthouse — a slim red-and-white-banded tower — is still operational; visitors can climb it for a sweeping view of the Gulf of Finland that on a clear day reaches the Estonian coast.
Tours run from Hanko's Eastern Harbour several times a week in summer (book through the tourist office or M/S Marina); the round trip including a guided walk on the island takes about three hours. Pre-booking is essential. The walk passes the old gun batteries, the lighthouse keeper's cottage now used as a small museum, and a stretch of granite shoreline grazed by hardy island sheep.