Wadden Seas are parts of seas or landscapes on the coast respectively. Characteristic of these landscapes is that Wadden Seas are particularly exposed to the tides. There are many Wadden Seas in the temperate zones all over the world. The sea accessible by wading is usually flooded twice a day during high tide. The areas drying out at low tide are called mudflats. The habitat is susceptible to pollutions, in particular to those caused by man. We deal with the natural landscape between the Dutch Den Helder and the Ho Bay in Denmark that covers 10,000 square kilometres in total. The Wadden Sea along the North Sea: National Park, UNESCO World Heritage natural site and the largest contiguous area of mudflats in the world. The North Sea coast is wilderness on the one hand, work of man on the other hand.