Heinisuo, located in Hämeenlinna, is a protected natural marsh area. There are various swamp types in Heinisuo. There is a stream in the bog area strating from a spring. The flying squirrel lives in the area and the swamp has a diverse bird population. Across the swamp and its nearby forests runs a marked hiking trail, part of the Hämeen Ilvesreitti trail. You can reach Heinisuo by turning from Highway 10 to Suvipielisentie, with a Heinisuo sign at the crossing.