The river Valserine is a tributary of the Rhône that flows for 47.6 kilometres from the Col de la Faucille in the Jura Mountains to its confluence with the Rhône at Bellegarde-sur-Valserine. The Valserine Valley has great charm; it includes the Pont des Pierres that spans the river between Montanges and Mulaz, as well as the Pertes de la Valserine just north of Bellegarde-sur-Valserine, a canyon in which during the dry season the Valserine runs underground.