Loch Ness is an extremely narrow and long lake, extending from the northeast to the southwest in the Inverness area of north Scotland. The lake is about 39 km long, but only 1.5 km wide, and has a maximum depth of 230 m and a mean depth of 132 m. Its water volume is the largest, and the surface area is the second largest next to Loch Lomond, in this country. The lake water flows out to Moray Firth through the Ness River. It is known as one of the most scenic lakes of this country, with an old ruined castle on the lakeside and surrounding mountain view. The lake is also so famous for the "Nessy", a world-famous unidentified organism. Investigations on Nessy have been carried out since 1962 by the Loch Ness Investigation, a voluntary organization with some scientists.

The drainage basin is still rich in woodlands and grasslands, having a low population density of 1.8 km-2. Nutrients inflow to the lake, therefore, is still in low level and the water remains oligotrophic and transparent. However, it is anxious that eutrophication may be caused by many tourists attracted by Nessy and by increasing activity of residents in the drainage basin.