The Doubs is a 453km long river in eastern France and western Switzerland, left tributary of the Saône. Its source is near Mouthe in the western Jura mountains.First it flows northeast, more or less along the French-Swiss border . Near Montbéliard it turns southwest, until it flows into the river Saône in Verdun-sur-le-Doubs, approx. 20 km northeast of Chalon-sur-Saône. Its entire course resembles an inverted letter U, with the northeastern corner the only point at which the Doubs flows into Switzerland as far as Saint-Ursanne.The Doubs flows through the following Departments of France, Cantons of Switzerland, and cities: Doubs : Pontarlier Neuchâtel  Jura : Saint-Ursanne Doubs : Montbéliard, Besançon Jura : Dole Saône-et-Loire : Verdun-sur-le-Doubs Tributaries include:  Loue Dessoubre The river forms several lakes:  Lac des Brenets  Lac de Moron  Lac de Biaufond