Duinen Terschelling is one of the larger islands in the Wadden Sea, characterized by sand dunes and an extensive intertidal mudflat surrounded by grassland, conifer crops, small villages and silt polders claimed from the sea. The Site was formerly part of Ramsar Site 1252 (Waddeneilanden, Noordzeekustzone, Breebaart) which was divided in six Sites following Natura 2000 borders in 2014. The site is of international importance for European threatened species of breeding birds such as little tern, northern harrier and western marsh harrier, and endangered species of flora such as pigmy rush and green-winged orchid. The dunes form a natural coastal defence against the erosive forces of the North Sea and they retain rain water ensuring freshwater supply. Human activities include tourism, conservation and research. The main threats to the Site’s ecological character are posed by groundwater extraction and tourism.