Loch Lomond is a freshwater loch lying on the Highland Boundary Fault, often considered the boundary between the lowlands of Central Scotland and the Highlands. Its surface area is 71 km2 (27 sq mi), and it has a volume of 2.6 km3 (0.62 cu mi). Of all lochs and lakes in Great Britain, it is the largest by surface area, and the second largest (after Loch Ness) by water volume.
The loch contains thirty or more islands (depending on the water level). Several of them are large by the standards of British bodies of freshwater. Inchmurrin, for example, is the largest island in a body of freshwater in the British Isles. As in Loch Tay, several of the islands appear to be crannogs, artificial islands built in prehistoric periods.
English travel writer, H.V. Morton wrote: "What a large part of Loch Lomond's beauty is due to its islands, those beautiful green tangled islands, that lie like jewels upon its surface".
A 2005 poll of Radio Times readers voted Loch Lomond as the 6th greatest natural wonder in Britain.