The main coastal towns are, from the west to the north-east, Minehead, Watchet, Burnham-on-Sea, Weston-super-Mare, Clevedon and Portishead. The coastal area between Minehead and the eastern extreme of the administrative county's coastline at Brean Down is known as Bridgwater Bay, and is a National Nature Reserve. North of that, the coast forms Weston Bay and Sand Bay whose northern tip, Sand Point, marks the lower limit of the Severn Estuary. In the mid and north of the county the coastline is low as the level wetlands of the levels meet the sea. In the west, the coastline is high and dramatic where the plateau of Exmoor meets the sea, with high cliffs and waterfalls.