as well as deep and flat areas that are permanently under water (sublittoral). Additionally there are smaller units around sensible places like breeding areas of coastal birds, sandbars of seals, places where migratory birds moult or geomorphological meaningful areas with natural surface structure. Zone 1 is principally closed for the public. Exceptions are made for the mudflat areas directly bordering the coastline, some routes for guided mudflat hiking tours and fishery. South of the Hindenburgdamm, facing the landside of Sylt, a human use of the first zone is completely prohibited (Zero use zone). This part is 12.500 ha big, whereof 3500 ha are permanently covered with water. Zone 2 forms a ‘buffer’ around the first zone, in which a sustainable use is possible. In protection zone 2 west of Sylt´s coast locates a protection area for small whales, e.g. the common porpoise, with a size of 124.000 ha. It is an important reproduction area of the porpoise, whose population declined about 90 per cent in the North Sea during the 20th century. Activities like swimming, sailing or traditional crab fishing are still allowed in the area, while international industry fishing, jet-skis, ship velocities over 12 knots, military activities and resource exploitation (sand, grit, gas, oil) should be prevented. Land, sea and mudflats The North Sea coast is very flat; in places the ocean floor only descends a few centimetres per kilometre. Twice a day the high tide carries sand, clay and silt into the Wadden Sea. The tidal range in Schleswig-Holstein´s part of the Wadden Sea accounts for between 1.5 m and 3.7 m, increasing from north to south. The lowest tidal ranges occur on Sylt's north coast, the highest in southern Dithmarschen. Everywhere in the Wadden Sea the amount of time the water needs to stream in is only 85% of the time it needs to run off again. Therefore the current of the water coming in, is much stronger and the low tide does not have the power to remove the sediments the high tide accumulated. Over 2/3 of the national park are covered with water permanently (sublittoral), 30% of mudflat that is lying dry during low tide and gets flooded with water during high tide (eulittoral). The rest is land area that only gets flooded under certain conditions (supralittoral). The water areas contain the offshore part of the park as well as huge tidal currents like the