 The lake is roughly triangular in shape with its inflow from Albysjön in the southern corner, and its outflow to Kalvfjärden in the north-eastern corner.It is separated from Albysjön by the peninsula Rävnäset, a municipal nature reserve covering 27 ha.It contains a wide range of rare species and is together with the nature and park surrounding Tyresö Palace one of the best locales for bats.