The coast of the North Sea presents a diversity of geological and geographical features. In the north, deep fjords and sheer cliffs mark the Norwegian and Scottish coastlines, whereas in the south, the coast consists primarily of sandy beaches and wide mudflats. Due to the dense population, heavy industrialization, and intense use of the sea and area surrounding it, there have been various environmental issues affecting the sea's ecosystems. Adverse environmental issues – commonly including overfishing, industrial and agricultural runoff, dredging, and dumping, among others – have led to a number of efforts to prevent degradation of the sea while still making use of its economic potential.