The Schleswig-Holstein Wadden Sea National Park () is a national park in the Schleswig-Holstein area of the German Wadden Sea. It was founded by the Parliament of Schleswig-Holstein on 1 October 1985 by the National Park Act of 22 July 1985 and expanded significantly in 1999. Together with the Lower Saxon Wadden Sea National Park, the Hamburg Wadden Sea National Park and those parts of Elbe estuary which are not nature reserves, it forms the German part of the Wadden Sea. The national park extends from the German-Danish maritime border in the north down to the Elbe estuary in the south. In the North Frisian area, it includes the mudflats around the geest-based and marsh islands and the Halligen (undyked islands). There, the mudflats are 40 km wide in places. Further south lie areas of mudflats which contain particularly large sandbanks. In addition to the plants and animals that are typical of the entire Wadden Sea, especially large numbers of porpoise, shelduck and eelgrass may be seen in the Schleswig-Holstein part. With an area of 4410 km ² it is by far the largest national park in Germany. Some 68% of its area is permanently under water and 30% is periodically dry. The land element consists mainly of salt marshes. Since 1990, the national park, including the North Frisian Halligen, has been designated as a UNESCO recognised biosphere. Together with other German and Dutch Wadden Sea areas it became a UNESCO World Heritage Site on 26 June 2009 because of its relatively undisturbed intertidal ecosystem and its unique biodiversity. Geography National park area The national park covers an area from the North Sea coast of Schleswig-Holstein by the Danish border in the north to the Elbe estuary in the south. In the northern area (roughly as far as Amrum), the national park boundary extends to the twelve mile territorial limit; to the south it reaches to about the three mile line. On the land side it runs in the sea 150 metres off the coast. Sea dykes and the foreland immediately in front of the dykes are not part of the national park; beaches are thus largely excluded from the protected zone. Also excluded from the national park are the inhabited areas in the sea, including the five German North Frisian Islands and the larger Halligen islands of Langeness, Hooge, Gröde, Oland and Nordstrandischmoor. Part of the park comprises uninhabited