Wadden Sea, Denmark [Photo Source: huanqiu.com]

4. Waddenzee in Denmark is an intertidal zone in the southeastern part of the North Sea. Visitors swarm into here to experience the interesting "Mudflat hiking". The earth's surface of this area is formed by sea water and wind force, and then destroyed to reform new deposit sediments. If the acceleration of sea level rising is beyond the expectation, there will be lack of sediments to remodeling the earth.