Loch Lomond is a freshwater Scottish loch which crosses the Highland Boundary Fault, often considered the boundary between the lowlands of Central Scotland and the Highlands. Traditionally forming part of the boundary between Stirlingshire and Dunbartonshire, Loch Lomond is currently split between the council areas of Stirling, Argyll and Bute and West Dunbartonshire. Its southern shores are about 23 kilometres northwest of the centre of Glasgow, Scotland's largest city. The Loch forms part of the Loch Lomond and The Trossachs National Park which was established in 2002.
Loch Lomond is 36.4 kilometres long and between 1 and 8 kilometres wide, with a surface area of 71 km2 making it the largest inland stretch of water in Great Britain by surface area. Within the United Kingdom, it is surpassed only by Lough Neagh and Lough Erne in Northern Ireland, although within the British Isles as a whole there are also several larger loughs in the Republic of Ireland.