West Frisian Islands

The West Frisian Islands form a sandy barrier between the North Sea and the tidal flats off the Dutch coast. Dunes face the open sea, while sheltered channels separate the islands from the mainland. The Vlie, between Vlieland and Terschelling, was a passage between the sea and the waters that became the Zuiderzee. Floods widened the old estuary in the thirteenth century, eroding peatland behind the islands and leaving a landscape of sandbanks and tidal flats through which ships had to find their way.