Lac Bersau

Lac Bersau is a mountain lake in the western Pyrenees, sitting within the commune of Laruns in the Pyrénées-Atlantiques department, inside the Ossau valley. Perched at 2,083 metres above sea level, it belongs to the well-known cluster of lakes referred to as the Ayous lakes, a scattering of glacial pools at the foot of the Pic du Midi d'Ossau, alongside neighbours such as Lac Gentau, Lac Roumassot and Lac de Casterau. Despite sitting close to these other pools, Bersau remains a separate body of water with its own footprint, tucked away from the busiest stretch of trail that runs past the more visited lakes in the group.

Where exactly is the lake?

Lac Bersau sits at coordinates 42.8392 N, -0.4947 W, inside a glacial cirque in the Ossau valley, directly below the Pic du Midi d'Ossau, whose 2,884-metre summit dominates the skyline and stays in view for most of the approach. The surrounding terrain is classic high-Pyrenean scenery: rocky ridgelines, open pastures once grazed by mountain flocks, and glacial boulders scattered across the slopes.

How big and how deep is it?

The lake covers roughly 0.125 km², a little over 12 hectares of surface water. Its maximum depth reaches 30 metres, which is notably deep for such a modest surface area and reflects the glacial origin of the basin it fills.

How do you get to Lac Bersau?

The standard approach starts in Pau, following the N134 to Gan and then the D934 towards Laruns. From Laruns the road continues toward the Col du Pourtalet as far as Gabas, where a turn leads to the car park at Lac de Bious-Artigues, sitting at 1,422 metres. This car park is the starting point for the popular loop hike that strings together the Ayous lakes. The path climbs past Lac Gentau on its way to the Refuge d'Ayous, while Lac Bersau lies just off this main route, which keeps visitor numbers noticeably lower than at the more exposed lakes along the direct path.

What else should hikers know before setting out?

Given the altitude — above 2,000 metres — the practical hiking season is largely limited to summer, from around June or July through September, once snow has cleared from the higher stretches of trail. The area sits among the most recognisable landscapes of the Ossau valley and borders the Pyrenees National Park, which helps explain the largely untouched character of the surroundings: open mountain pasture, bare rock ridges, and small glacial lakes set beneath high peaks.

Frequently asked questions

Is Lac Bersau the same lake as Lac Gentau? No. They are two separate lakes within the same Ayous group, close to one another but distinct in size, depth and position along the trail.

How long does it take to reach the lake? The hike starts at the Bious-Artigues car park (1,422 m) and continues through the chain of Ayous lakes; given the climb to over 2,000 metres, it is worth planning for a full day out.

Is there anywhere to stay overnight near the lake? The Refuge d'Ayous, along the trail linking the Ayous lakes, serves hikers visiting this part of the valley.

Is it worth visiting Lac Bersau if it's less well known than its neighbours? Yes — sitting off the main path means fewer people and a quieter atmosphere than at the more popular lakes in the same group.