The southern part of Föhr is made up of sandy soils dating back to the glacial period. It is a low hilly island with a few cliffs and beaches along the borders. The northern part is reclaimed marshland. Along the edges of this polder lie salt marshes and tidal flats. There are no dunes, but there are heath lands and planted woods. Lots of geese and shorebirds stop by Föhr when migrating and little terns brood on the island. The natterjack toad and the moor frog also live on the island.
In the south of the island, you can recognize grave mounds, which date back to the Bronze Age. There is also a Viking fort. There are 17 villages and a small city (Wyk) on Föhr. Wyk has an old and renowned spa.