Lac de Biaufond

Lac de Biaufond is a reservoir on the Doubs river, right on the Swiss-French border near Les Bois in the Swiss canton of Jura (Franches-Montagnes). It sits at about 610 m above sea level, covers roughly 47 hectares and was formed by the 15 m high Refrain dam. The water belongs partly to Switzerland and partly to France (Doubs department).

Where is Lac de Biaufond exactly?

The lake fills a deep, steep-sided valley where the river itself marks the frontier. The hamlet of Biaufond has a geographic quirk: it is the only place where the cantons of Neuchâtel and Jura touch, along a stretch of just 150 metres. A boundary stone in the flooded section of the valley marks the point where the two cantons meet France.

What will you see?

A calm sheet of water framed by wooded rock slopes, clear enough that fish are visible near the shore. At the Biaufond bridge the national border runs along the centre line of the roadway, so a single step takes you from one country to the other. The reservoir also matters for wildlife: in winter it hosts a significant population of wintering waterbirds, so bring binoculars.

On the Swiss side a restaurant with a gîte offers food and a place to rest after a walk. The Saut du Doubs waterfall (about 27 m high) is close by, and the Châtelot dam lies further downstream.

How to spend a day here

• On foot. A loop from Biaufond takes in Lac de Biaufond and the smaller Lac du Cul des Près: about 7.6 km, around 500 m of climbing and roughly 4 hours.
• Through the gorge. The Combe de Biaufond route uses metal ladders, wooden steps and fixed walkways. The longer walk from Biaufond to the Vieilles Femelles viewpoint passes the Échelles de la Mort (about 19 km, nearly 7 hours, graded difficult). It is not advised for anyone prone to vertigo.
• By bike. A loop from La Chaux-de-Fonds that includes the lake is about 41 km with some 770 m of ascent.
• For the view. A path on the French bank leads to the Cendrée belvedere, with views toward the Échelles de la Mort.

How do you get there?

A car is the easiest option. Trails start from the car park on the D464 at the Biaufond bridge. From the Swiss side the approach follows narrow roads from the Les Bois and La Chaux-de-Fonds area, so drive carefully. On the French side, at Fournet-Blancheroche, there is a motorhome stopover.

When to visit

Spring and early autumn suit hiking best. Winter appeals to birdwatchers, although paths in the gorge can be slippery.

Frequently asked questions

Is Lac de Biaufond in Switzerland or France? Both: Switzerland (canton of Jura, Les Bois) and France (Doubs department).

How big is the lake? About 47 hectares, at an altitude of around 610 m.

Can you eat or stay overnight nearby? The Swiss side has a restaurant with a gîte. Motorhome travellers can use the stopover in Fournet-Blancheroche.

Is the Combe de Biaufond trail difficult? Yes. It involves ladders, steps and walkways, so it calls for good fitness and a head for heights.