Loch Lomond (lŏkh lō´mənd, –mən), largest freshwater lake in Great Britain, 23 mi (37 km) long and from 1 to 5 mi (1.6–8.1 km) wide, in Argyll and Bute, West Dunbartonshire, and Stirling, W Scotland. The Leven River drains it into the Clyde. At the southern end of the lake, near its outlet, are numerous wooded islands. The northern end is overlooked by Ben Lomond (3,192 ft/973 m high). The hydroelectric power plant at the northwestern end of the lake is fed by water from Loch Sloy. Loch Lomond has numerous associations with Rob Roy, and a cave there was once used as a refuge by Robert I. The lake is a popular tourist attraction; it and surrounding areas are in Loch Lomond and the Trossachs National Park.
Loch Leven (lŏkh lē´vən), lake, 31/2 mi (5.6 km) long, Perth and Kinross, E Scotland. Its several islands include Castle Island, with the ruins of the castle in which Mary Queen of Scots was imprisoned in 1567–68, and St. Serf's, with the ruins of an ancient priory. The Leven River, outlet of the lake, flows E through Fife to the Firth of Forth.