Lake Leman is the largest body of fresh water in western Europe
, with an area of 528 km² (348km² in Switzerland and 234km² in France) and containing 89 billion m3 of water. It is principally fed by the Rhône, which flows from one end to the other and leaves the lake at Geneva.
The lake forms an elongated crescent between the mountainous landscapes of the Alps and the Jura. Its northern and southern sides are only 4 km apart in the “little lake” to the west, but more than 13km apart in the “large lake” between Morges and Amphion. The waters are deepest, 310m in the “upper lake” to the east between Lausanne and Evian. The lake has a great moderating in-fluence on the climate of the region and acts as a bird sanctuary.