The south-central part of Sri Lanka is a rough plateau cut by a range of mountains whose highest peak is Pidurutalagala, 2,524 m (8,281 ft). Narrow coastal plains skirt the mountainous section on the east, south, and west, but in the north the extensive coastal plain fans out, reaching from the eastern to the western shores of the island. Five-sixths of the land is less than 300 m (1,000 ft) in elevation. Numerous rivers and streams flow seaward in all directions from the central mountain area; the longest river, flowing northeastward, is the Mahaweli Ganga (332 km/206 mi).