 It consists of 1600ha of marshland reclaimed from the sea (called a "Koog" in German) and protected with a dike in 1696 to secure the land connection between Büsum and Wesselburen.The first part of its name was adopted in honor of Hedvig Sophia of Sweden, wife of Duke Frederick IV of Schleswig-Holstein-Gottorp.The coat of arms is a modified version of the duke's seal and shows a swan holding an eel.