The crescent-shaped lake, formed by a withdrawing glacier, narrows around Yvoire on the southern shore, the lake can thus be divided into the "Grand Lac" (Large Lake) to the east and the "Petit Lac" (Small Lake) to the west.
It lies on the course of the Rhône River. The river has its source at the Rhone Glacier near the Grimsel Pass to the east of the lake and flows down through the Canton of Valais, entering the lake between Villeneuve and St. Gingolph, before flowing slowly towards its egress at Geneva. Other tributaries are La Dranse, L'Aubonne, La Morges, Venoge, and Veveyse.
The Lake Geneva has an alpine character. The Chablais Alps border its southern shore, the western Bernese Alps lie over its eastern side. The high summits of Grand Combin and Mont Blanc are even visible from a few places.
By the 1960s, the lake had ceased being a transport artery for commercial and construction materials. In the late 1960s pollution made it dangerous to swim at some beaches of the lake; indeed, tourists taking a ride in the local submarine had near zero visibility (it was eventually sold). By the 1980s, intense environmental pollution (eutrophication) had almost wiped out all the fish. Today, pollution levels have been dramatically cut back, and it is again considered safe to swim in the lake. Major leisure activities practiced include sailing, wind surfing, boating (including water skiing and wakeboarding), rowing, scuba diving and bathing.
As an interesting historical and scientific footnote, in 1827, Lake Geneva was the site for the first measurement of the speed of sound in (fresh) water. French mathematician Jacques Charles François Sturm and Swiss Physicist Daniel Collodon used two moored boats, separated by a measured distance, as the transmit and receive platforms for the sounds of exploding gunpowder. The loud airborne sound coupled into the lake, establishing a loud underwater sound that could be measured at a distance. The flash of the exploding gunpowder provided the visual starting cue for the timepiece, and the underwater explosion sound striking a bell provided the finish cue.
The shore between Nyon and Lausanne is called La Côte because it is "flatter". Between Lausanne and Vevey it is called Lavaux and is famous for its hilly vineyards.
The lake's surface is the lowest point of the cantons of Valais and Vaud.
Compagnie Générale de Navigation sur le lac Léman (CGN) operates boats on the lake.