For millions of years, the meandering little River Doubs had dug itself into the limestone of the Jura by erosion. Since a rock fall about 14,000 years ago, the water has dammed up to form a lake nearly 4 kilometres long but barely 200 metres wide. As you move north-east towards the end of the lake, the initially flat shores turn into steep sides. Here, the white chalky cliffs, up to 80 metres high, drop down into the lake, some almost vertically. World records have been set for jumping off these cliffs into the depths of the Lac des Brenets.

During the summer season, the bathing lake is used for boat trips. There is a regular service between Les Brenets and the Saut du Doubs waterfall. However, the 27 metre high waterfall can also be reached by a one-hour walk from Les Brenets.

From the Saut du Doubs, the footpath continues along the Doubs, past the smaller Lac de Moron. For 43 km of its length, the wild and romantic valley of the Doubs forms the border between Switzerland and France. This sparsely populated area is a paradise for fishermen and walkers. In summer, the latter appreciate the shade cast by the trees overhanging the footpaths alongside the twisty little river.

One very special experience is the nearly 80 kilometre long four-day Doubs Hike from Les Brenets to the historic Jura town of St. Ursanne. Of course, the walk can also be completed in separate one-day stages. From Le Locle, a narrow-gauge railway takes you to Les Brenets in seven minutes, and at the end of each stage of the walk there is a postal bus service to take you back up out of the deep Doubs valley to the Jura plateau.

From May to October, there is a bus service from the harbour in Les Brenets to the cave mills at Col des Roches, a crossing-place into France. From the 17th century, the cave was used as the site of a mill and sawmill powered by the underwater stream. Abandoned for over 100 years, the site has been renovated and is open for interested visitors.