The entire coastal region is part of the Schleswig-Holstein Wadden Sea National Park. In the south is the Eiderstedt peninsula, where the River Eider joins the sea. The North Frisian Islands are also part of the Nordfriesland district. There are five large islands (Sylt, Föhr, Amrum, Pellworm and Nordstrand) and ten smaller islets known as Halligen.