World Natural Heritage

The Wadden Sea of the North Sea is a tidal area, about 9,000 km² in size, 450 kilometers long and up to 40 kilometers wide between Denmark in the north-east and the Netherlands in the south-west.The bottom of the North Sea that is exposed at low tide is called mud flats.It is the largest Wadden Sea in the world.

The tideland is flooded twice a day during high tide and dries up again at low tide, with the water often draining away through deep streams (tidal creeks).The time interval between a high tide and a low tide is six hours and twelve minutes on average.The Wadden Sea, which was formed around 7500 years ago, serves as a resting place and food source for many birds and fish.

Almost the entire Wadden Sea is under nature protection.The German part (except for the major estuaries that are important shipping routes) is protected as a national park and has been a UNESCO World Heritage Site since June 26, 2009.

The sea currents formed sandbanks that piled up in the southern Wadden Sea to form barrier islands (East Frisian and West Frisian Islands).This process runs continuously.In the last few centuries, for example, Bant and Buise disappeared into the sea, and Memmert and the Kachelotplate were created instead.Apparently, other sandbanks like Lütje Hörn cannot establish themselves permanently.

human influence

Ever since humans began to change the coast through extensive settlement measures around 1000 years ago, and especially since they switched from terp building to dyke building, the landscape has changed dramatically.Since the Middle Ages, he has diked about a third of the area of the Wadden Sea and transformed it into mainland.By completely preventing flooding with the dykes and water only flowing from land to sea, he desalinated the salt marshes so that after desalination ponds and polders with fertile marshland emerged.

Until the Middle Ages, people mainly lived on natural elevations on the mudflats.The population was correspondingly low.Only with the development of larger coastal protection projects did people begin to settle down in large numbers.They built artificial elevations, the terps.From this, ring dykes developed, which were expanded by summer dykes, and finally winter dykes came along.All along the coast, people began to establish themselves permanently and to protect themselves from the sea.

After the severe storm surges of 1953 in the Netherlands and 1962 in Germany, the dyke lines were straightened, some new dykes were built and the rest were raised by at least one meter and the angle of inclination was further flattened, so that the modernized dykes have withstood all further floods to this day.Although the storm surges of 1976 and 2007 set new record high water levels, there were no more fatalities.


Just as numerous shorebirds breed in the sheltered mudflats, the nutrient-rich area is a regular resting place for migratory birds on Atlantic routes.Approximately ten to twelve million birds migrate through the Wadden Sea, including specimens of numerous endangered species.The Wadden Sea is an indispensable area for around 50 species from the northern hemisphere.From about 20 large populations, more than half of the individual animals spend at least part of their lives in the Wadden Sea, about ten species are almost exclusively found in the Wadden Sea at times.

Above all, however, large numbers of migratory birds use the Wadden Sea to rest.Of the numerous resting birds that use the Wadden Sea on the migration between subarctic areas and Africa.Some bird populations have increased again since hunting in the Wadden Sea has been almost completely prohibited and the Wadden Sea itself is subject to various nature conservation regulations.Species that were completely extinct in the Wadden Sea and immigrated again from other regions in the 20th century include the white-tailed eagle and the great egret.


After large whales disappeared completely from the Wadden Sea in the early modern period and gray seals were able to reestablish themselves after being driven out for several hundred years, three species of mammals occur in the Wadden Sea: the common seal, the most common mammal with a distribution center in the north of the Wadden Sea, the gray seal,found mainly in the south, and the harbor porpoise, which is found throughout the North Sea but which often retreats to the sea/wads transition zone in the northern Wadden Sea, particularly when giving birth.Both the number of gray seals and harbor seals has increased in recent decades.

natural reserve

Due to the uniqueness of the Wadden Sea and a growing awareness of the threat to the system from human uses such as tourism, fishing and shipping since the second half of the 20th century, the Wadden Sea is subject to a number of international protection agreements, which are supplemented by various national nature conservation measures.

UNESCO recognized the German and Dutch parts of the Wadden Sea as a biosphere reserve in 1991 and thus placed them under international protection.On June 26, 2009, UNESCO approved the joint application by the Netherlands, Lower Saxony and Schleswig-Holstein, but not Hamburg and Denmark, to have the Wadden Sea protected as a natural world heritage site.