The tidal flats between Den Helder in the Netherlands and Esbjerg in Denmark are the largest continuous tidal flats in the world and one of the last areas in Europe where nature can still develop to a great extent without human influence. So that this can continue, the German coastal states declared it as National Parks: in 1985 the Schleswig- Holstein Wadden Sea, in 1986 Lower Saxony Wadden Sea and in 1990 the Hamburg Wadden Sea. The Wadden Sea in Schleswig-Holstein, Niedersachsen and the Netherlands was placed on the UNESCO World Heritage List in 2009.