A long, narrow freshwater lake in the dunes at the western end of the island, the Hammersee is the only body of fresh water on the East Frisian chain. It sits behind the foredunes about a kilometre west of the village, surrounded by reeds and birch scrub, and is reached on foot or by bike along a sandy track from the western edge of town.
The lake itself is a quiet, slightly melancholy place — rarely more than a handful of visitors — and the surrounding scrub is excellent for birds: marsh harriers in summer, reed buntings, and large numbers of waterfowl in the migration seasons. A wooden boardwalk and a small bird hide give views over the water. Swimming is not allowed.