About 70% of the earth's surface is covered with ocean water; the coastal line along the landmasses is accordingly long. Therefore it is very surprising that the coastal section between Den Helder (Netherlands) and Esbjerg (Denmark) - the Wadden Sea - is unique in the world. The evolution of this magnificent area has been developing for over 10,000 years and it is still going on, for which the interaction of following aspects was (and still is) necessary: The inclination of the seafloor is relatively low. Sometimes it hardly inclines a few inches per mile. In these areas light and fine material (i.e. sand or clay) can easily be deposited. The rivers frequently move fine sand and clay particles from the land into the mud flats, where those particles are deposited. Further accumulation is caused by particles from the open sea. The mud flats fall dry twice a day. During low tide, the sand layers are dried and get carried away by the wind which blows landwards. (forming dunes) Sandbanks, reefs and isles in the coastal section break the waters and the currents from the open sea. Therefore, the fine sand and clay particles can be deposited on the ground. The interaction of these forces shape the coastal line unrestrictedly; but seen in the long term the loss of land is caused by the rising sea level.