Lac de Longet

Lac de Longet is a high-mountain lake sitting on the territory of Saint-Paul-sur-Ubaye, in the Alpes-de-Haute-Provence department, right against the French-Italian border. Resting at 2,641 metres above sea level and covering just under three hectares, it marks the highest point of the entire Ubaye valley. It is here, too, that the Ubaye river itself rises — a tributary of the Durance that then flows the length of the valley bearing its name.

Where exactly is the lake?

Lac de Longet lies within the Chambeyron-Oronaye massif, a range stretching roughly 20 km from the Col du Longet to the Col de Larche. The lake sits just a short distance from the Col de Longet, a pass that forms the natural crossing point into Italy. From the surrounding ridgelines, hikers can pick out several regional summits: Tête des Toillies (3,175 m), Roche Noire (3,134 m) and Cristillan (2,957 m), with Mont Viso (3,841 m) visible on clear days across the border in Italy. A handful of smaller satellite tarns sit just above the main lake.

How do you get there?

Most visitors start from Maljasset, the last hamlet in the Haute Ubaye, reached by the D25 road out of Saint-Paul-sur-Ubaye. From there, a trail follows the Ubaye upstream to its source, with the climb typically taking 4 to 4.5 hours depending on fitness and season. The route is demanding but achievable for well-prepared hikers, with no technical climbing gear required. The area also forms part of the multi-day GRP Tour du Chambeyron, a long-distance route popular with hikers exploring the Alps of southern France. An alternative approach comes from the Italian side, starting in Chianale and crossing the Col Agnel — though this option means crossing the international border on foot.

Nature and geology around the lake

The surroundings sit within the alpine vegetation belt, which gives way further up to the nival zone of bare rock and permanent snow. Close to the shoreline, small waterlogged meadows host bicolour sedge, alongside patches of limestone scree; botanists have catalogued more than twenty distinctive plant species in the immediate area. Among the wildlife found here are the rock ptarmigan and the bearded vulture, both considered particularly significant for this type of high-altitude habitat. The bedrock itself combines siliceous rock dating to the Permian period with schists and marbles from the Jurassic and Cretaceous — remnants of the ancient Tethys Ocean roughly 150 million years old, later reshaped by Alpine mountain-building around 40 million years ago.

Fishing at Lac de Longet

The lake falls under first-category fishing waters and follows the specific regulations that apply to mountain lakes. It is stocked with common trout, making it a destination for anglers visiting the Haute Ubaye during the summer season — checking local fishing rules before setting out is recommended.

Frequently asked questions

How high up is Lac de Longet? The lake sits at 2,641 metres above sea level, making it the highest point in the Ubaye valley.

How long does the hike to the lake take? Starting from Maljasset, the climb usually takes between 4 and 4.5 hours one way.

Can you fish at the lake? Yes — it is classified as first-category water and stocked with common trout, though mountain-lake fishing regulations apply.

Is Mont Viso visible from the lake? On clear days, Mont Viso (3,841 m) can be seen across the Italian border from the surrounding ridges.

Is there a route from the Italian side? Yes, an alternative approach starts in Chianale and crosses the Col Agnel into France.