Loch Ness is the largest lake in Great Britain, being 23 miles long, one mile wide, and almost 900 feet deep in places.
Geologists believe that the present day Loch Ness dates from the end of the Ice Age. During the ice age, the Great Glen was occupied by a huge glacier which filled the valley above the level of the present watershed, and extended into the Moray Firth. This glacier found the shattered rock along the fault easy to erode, which accounts for the great depth of Loch Ness to 600 feet below sea level. The underwater perimeter of the lake is glacially smoothed and very steep. Above Foyers Bay at the deepest section, there is 500 feet of water only 60 feet out from the bank.
Loch Ness is most famous for unsubstantiated reports, some fraudulent, of the "Loch Ness Monster", a large, dinosaur-shaped creature said to inhabit the loch. The size of the lake makes a full search of the lake unfeasible.