Lake Annecy, one of the cleanest in Europe,because of strict environmental regulations introduced in the 1960s. Located in Haute Savoie, as is Lake Geneva. It is a popular tourist destination known for its swimming and water sports. It measures 14.6 kilometers for a width of 800 to 3300 meters, making it the second lake in France after Lake Bourget. It consists of two distinct basins, the "Grand" and the "Petit lac" separates the lake in two between the Roc de Chère and the castle of Duingt.
Public domain, the lake formed about 18,000 years ago when the great Alpine glaciers melted. It is fed by seven streams and torrents, born in the surrounding mountains: the I, the dead water, the Laudon, the Bornette, the Biolon and by a powerful sub-lacustre source, Boubioz, which springs 82 meters from depth.
It is bordered on the east by the Massif des Bornes (the Tournette - 2,351 meters, the Teeth of Lanfon, Mount Veyrier and Mount Baron) and to the west by the Bauges massif (Semnoz and Roc des Bœufs), to the north by the agglomerations of Annecy and to the south by the valley towards Faverges which extends the Bout-du-Lac.
The lake can be reached on foot or by bike for about forty kilometers.
The lake pours its overflow of water into the Thiou that feeds the Fier at 1,500 meters north-west of Annecy, which flows itself into the Rhone. It is a very attractive tourist place, known for its numerous nautical activities, paragliding, and its environmental qualities allowing the observation of a preserved nature.