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The Wadden Sea


The Wadden Sea is part of the Wadden Sea coast of the North Sea. Typical are the sandbanks that dry up during low tide, separated by more or less deep channels. We usually find a muddy strip of slit along the coast. With every tide, the salt water of the North Sea is pushed up through the tidal inlets between the Wadden islands into the Wadden Sea. A number of rivers flow into the Wadden Sea. In Germany the Ems, the Weser and the Elbe, in the Netherlands (via the locks in the Afsluitdijk) the IJssel and other rivers and canals draining into the IJsselmeer.


During the coldest period at the end of the last Ice Age, about 18,000 years ago, the sea level was over a hundred meters below the current sea level. At that time, the North Sea bed was largely dry. After this period the ice caps melted, causing the sea level to rise and water to run into the North Sea. About 7000 years ago, the coastline was roughly in the vicinity of the current coast. Wave action and tidal movements transported sediment from the sea to the coast. This sediment was deposited along the coast and in the nearby hinterland, which consequently rose slightly higher each time and did not drown because of the rapidly rising sea level. In the German Bend and along large parts of the Dutch and Flemish coast, tidal flats with tidal channels (sea channels) and salt marshes were formed. On the North Sea side, sandy beach walls were formed.

After this, the sea level upsurge decreased and from about 5000 years ago, the first continuous beach walls in the western Netherlands could be preserved. The tidal channels in the hinterland often silted up and the former mudflats and salt marshes became covered with a peat bog. In the Northern Netherlands (roughly east of Vlieland) the situation was different. The beach walls were not contiguous, they have always been interrupted by tidal channels that led to the underlying wadden sea and salt marsh area. These interrupted beach walls formed the core of most of the Wadden islands.

The Wadden Sea Region has always been dynamic over the past 7000 years. Tidal channels have regularly shifted, and the boundaries of the Wadden sea nd salt marsh area and the location of the Wadden Islands have also regularly shifted.

Flora and Fauna

The shallow, relatively warm water of the Wadden Sea with its rich soil life provides great living conditions for large numbers of plants and animals. About 250 plant species occur only in the Wadden Sea. Seals give birth there, fish spawn there, and birds forage on worms and shellfish in preparation for their annual migration. Due to its role as a nursery and stopping place, the Wadden Sea has great ecological value.

The Wadden Sea was once full of sea grass: in 1932 the surface was more than 150 km². The seagrass beds have largely disappeared. But there are signs of recovery, seagrass is being sown in the hope that this biotope and the associated organisms will recover.


Most of the Dutch Wadden Sea is a protected natural monument and has been designated a Biosphere Reserve by UNESCO. The island of Schiermonnikoog, the Lauwersmeer area and the Dunes of Texel are Dutch National Parks. Large parts of the German part of the Wadden Sea are also protected as national parks: the Hamburg Wadden Sea National Park, the Lower Saxon Wadden Sea National Park and the Schleswig-Holstein Wadden Sea National Park. Within these three parks there are three zones in which different protection regimes apply. Denmark has the Vadehavet National Park. At an international Wadden conference held in November 2005, it was decided to register the Dutch and the German parts for the World Heritage List. On June 26, 2009, the Dutch-German Wadden Sea became a Unesco World Heritage Site. The Danish part was also placed on the World Heritage List on 23 June 2014.

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