The coastline is severely indented, creating a number of large sea lochs, such as Lochs Resort and Seaforth, which form part of the border with Harris, Loch Roag, which surrounds the island of Great Bernera, and Loch Erisort. The principal capes are the Butt of Lewis, in the extreme north, with hundred foot (30 m) cliffs (the high point is high) and crowned with a lighthouse, the light of which is visible for ; Tolsta Head, Tiumpan Head and Cabag Head, on the east; Renish Point, in the extreme south; and, on the west, Toe Head and Gallon Head. The largest island associated with Lewis is Bernera or Great Bernera in the district of Uig and is linked to the mainland of Lewis by a bridge opened in 1953.