The Rhône is one of the major rivers of Europe and has twice the average discharge of the Loire (which is the longest French river), rising in the Rhône Glacier in the Swiss Alps at the far eastern end of the Swiss canton of Valais, passing through Lake Geneva and running through southeastern France. At Arles, near its mouth on the Mediterranean Sea, the river divides into two branches, known as the Great Rhône (French: le Grand Rhône) and the Little Rhône (le Petit Rhône). The resulting delta constitutes the Camargue region.
The Rhône rises as an effluent of the Rhône Glacier in the Valais, in the Swiss Alps, at an altitude of approximately 2,208 meters (7,244 ft). From there it flows south through Gletsch and the Goms, the uppermost, valley region of the Valais before Brig. Shortly before reaching Brig, it receives the waters of the Massa from the Aletsch Glacier. It flows onward through the valley which bears its name and runs initially in a westerly direction about thirty kilometers to Leuk, then southwest about fifty kilometers to Martigny.
Down as far as Brig, the Rhône river is a torrent; it then becomes a great mountain river running southwest through a glacier valley. Between Brig and Martigny, it collects waters mostly from the valleys of the Pennine Alps to the south, whose rivers originate from the large glaciers of the massifs of Monte Rosa, Dom, and Grand Combin.
At Martigny, where it receives the waters of the Drance on its left bank, the Rhône makes a strong turn towards the north. Heading toward Lake Geneva, the valley narrows, a feature that has long given the Rhône valley strategic importance for the control of the Alpine passes. The Rhône then marks the boundary between the cantons of Valais (left bank) and Vaud (right bank), separating the Valais Chablais and Chablais Vaudois. It enters Lake Geneva near Le Bouveret.