|From Wikipedia: The North Frisian Islands are a group of islands in the Wadden Sea, a part of the North Sea, off the western coast of Schleswig-Holstein, Germany and Jutland, Denmark. The German-ruled islands are part of the Schleswig-Holstein Wadden Sea National Park and the Kreis (district) of Nordfriesland. The Danish-ruled islands belong to Sønderjyllands Amt. Occasionally Heligoland is also included in this group.|
There are five larger islands and ten tiny islets. The names of the large islands are Sylt, Föhr, Amrum, Nordstrand and Pellworm. The islets are called Halligen. In medieval times the present-day islands Nordstrand, Pellworm as well as the Halligen were part of the large island of Strand. This island was torn to pieces in a disastrous storm tide in 1634.