Lac du Bourget, also locally known as Lac Gris or Lac d'Aix, is a lake at the southernmost end of the Jura Mountains in the department of Savoie, France. It is the deepest lake located entirely within France, and either the largest or second largest after Lac de Grand-Lieu depending on season.The largest town on its shore is Aix-les-Bains. Chambéry, the capital of Savoie, lies about 10 km south of the lake. It is mainly fed by the river Leysse, and drains towards the river Rhône through the Canal de Savières, an artificial channel. It is a Ramsar site. The extinct bezoule was found only in this lake.The lake was formed during the last period of global glaciation in the Alps  during the Pleistocene epoch. It has a surface area of 44.5km2. The long and narrow north-south axis of the lake extends 18 km in length, and ranges between 1.6 km and 3.5 km in width. The lake's average depth is 85 m, and its maximum depth in 145 m.The lake is bordered by the steep summits of the Mont du Chat and the Chaîne de l'Épine on the west, and Bauges Mountains on the east, which form its shores.