By volume, the largest body of water in the United Kingdom is Loch Ness, located in the Scottish Highlands. Loch Ness is a freshwater loch (a Scottish term for a lake) known for its legendary creature, the Loch Ness Monster or "Nessie." While Loch Ness is not the largest in terms of surface area, it holds the largest volume of water among all the lakes in the United Kingdom, with an estimated volume of about 7.5 cubic kilometer so (1.8 cubic miles).