The highest point in the county is the summit of [[Sawel Mountain]] () on the border with [[County Tyrone]]. Sawel is part of the [[Sperrin Mountains]], which dominate the southern part of the county. To the east and west, the land falls into the valleys of the [[River Bann|Bann]] and [[River Foyle|Foyle]] rivers respectively; in the south-east, the county touches the shore of Lough Neagh, which is the largest lake in Ireland; the north of the county is distinguished by the steep cliffs, dune systems, and remarkable beaches of the Atlantic coast.