In summary
• Hiking trail of 15.7 km – 751 m of positive elevation gain
• Loop circuit starting from the lake of Bious-Artigues
• Estimated duration: 6h40
• Difficulty: Medium
• Constant view of the Pic du Midi d’Ossau
• Crossing of five lakes: Roumassot, Miey, Gentau, Bersau, and Castérau
• Stop at the refuge d’Ayous
• Departure: municipality of Laruns (64440), Ossau valley, Pyrénées
• Maximum altitude: 2,096 m
• Signage: GR®10
The trail of the Lacs d’Ayous offers one of the most beautiful panoramas of the Pyrenees. This loop around five glacial lakes winds through forests, alpine pastures, and high-altitude passages, continuously showcasing the majestic Pic du Midi d’Ossau.
A quiet departure from the lake of Bious-Artigues
The circuit begins at the edge of the lake of Bious-Artigues, a vast high-altitude mirror popular with hikers. An upper parking area allows direct access to the start, but it fills up quickly during peak season. In case of crowds, a second parking area located lower down requires about thirty minutes of warm-up.
From the very first meters, the route runs along the left bank of the lake, before entering a forest where humidity and shadows accompany a gradual ascent to the Pont de Bious, at nearly 1,550 m altitude.
A winding ascent to the first lakes
The red and white signage of the GR®10 guides the step into the pastoral world of the summer pastures. The path rises in wide switchbacks, passes through a beech grove, and then emerges onto meadows where herds often graze.
The lake of Roumassot appears first. Its calm surface is often swept by the morning light. Just above it, a waterfall announces the lake of Miey, smaller and more discreet. Silence reigns at these altitudes, broken only by the cries of marmots.
The refuge d’Ayous and lake Gentau: the heart of the route
A final promontory leads to the lake Gentau, next to which stands the refuge d’Ayous. The image is striking: the waters reflect the Pic du Midi d’Ossau, a true rocky sentinel that dominates the scene at 2,884 m.
From the refuge, the trail climbs again. A ridge then leads to the lake Bersau, resembling a turquoise basin nestled beneath the peaks. This is the highest point of the loop (2,096 m).
From the pass to the return: the mineral world of Pic Castérau
From the pass, the landscape becomes rockier. The descent begins towards the lake Castérau, nestled in an austere basin. Lower down, the path plunges into the scree and then reaches the valley floor via a series of switchbacks.
The bridge of Bious, reached below, marks the end of the main loop. Then, it is just a matter of following the forest path back to the starting point or extending a bit via a trail around the lake of Bious-Artigues.
Practical information and advice
- The circuit is well marked and the paths clearly defined.
- In summer, plan for an early departure: the parking lots are full by 8:30 AM.
- The refuge d’Ayous allows for water refills.
- Count about 6h40 of walking without breaks.
- Be aware of possible snow cover in spring or autumn.
- Bring suitable clothing: the wind can be surprising at the pass.
A hike between lakes and Pyrenean peaks
This circuit at the Lacs d’Ayous is not just a simple succession of bodies of water. Each lake has its own atmosphere, relief, and particular reflection of the Pic du Midi d’Ossau, ever-present and changing according to the angle and time of day.
Walking here means accepting the elevation change as a necessary step towards breathtaking panoramas, between forests, high moors, and mountain silence. Ideal for hikers in search of raw nature and striking reliefs.
