Loch Lomond, largest of the Scottish lakes, lying across the southern edge of the Highlands. It forms part of the boundary between the council area of Stirling and the council area of Argyll and Bute. The council area of West Dunbartonshire forms its southern shore; the historic county of Dunbartonshire encompasses not only its southern but its western shore as well. Loch Lomond extends about 24 miles (39 km), widening south in the shape of a triangle. Although its surface is only 23 feet (7 metres) above sea level, its glacially excavated floor reaches a depth of 623 feet (190 metres). It drains by the short River Leven into the River Clyde estuary at Dumbarton. The scenery ranges from rugged, glaciated mountains with elevations above 3,000 feet (900 metres) in the north to softer hills and islands in the south. Within very easy reach of the metropolitan region of Glasgow, it is a favourite resort for the urban dwellers. The chief lakeside resort settlements are Balloch, Ardlui, Inversnaid, Balmaha, Luss, Rowardennan, and Tarbet. At Inveruglas there is a hydroelectric power station.