Lac de Coiselet is an artificial lake on the border between the Ain and Jura départements. It is the confluence of the Bienne and Ain rivers. It was created in 1970 when the Coiselet dam was impounded.
Cliffs surround the lake on all sides, offering spectacular scenery. Numerous footpaths nearby offer exceptional views of the lake and the Ain Valley.
Swimming is permitted but not supervised on the Chancia beach.
The lake is also very popular with anglers, renowned for its predator fishing (pike, perch and pike-perch).