On an island that was once a naval port, this museum housed in a handsome 16th-century granary recounts local history and the importance of water transport. It also has a number of exhibits about the history, flora and fauna of Lake Saimaa, including a 12-minute video about the underwater world of Torsti, an endangered ringed seal pup living in the lake. Exhibits on the ground floor are more interesting than those upstairs.
Outside, there's a group of historic watercraft to board (open mid-May to mid-September). These include the SS Mikko. Information about the town and region, including the Linnansaari National Park, is available from the ground-floor ticket office/information desk.