Lac de l'Aiguillette

Lac de l'Aiguillette is a mountain lake in the commune of Les Houches, in the Haute-Savoie department of France, sitting at the southern tip of the Aiguilles Rouges range, right across the valley from the Mont Blanc massif. The lake occupies a high plateau known as Carlaveyron and counts as the largest body of water inside the nature reserve that surrounds it. The setting is classic glacial terrain — rocky ridgelines, alpine pastures, and shallow pools scattered across a wide basin, all mirroring the peaks above.

Where exactly is the lake?

Lac de l'Aiguillette (roughly 45.925 N, 6.8111 E) sits on a plateau carved by glaciers that retreated tens of thousands of years ago, leaving behind a broad, bowl-shaped amphitheater. The basin lies beneath the summit of Aiguillette des Houches (2,285 m), which delivers sweeping views over the Mont Blanc massif on one side and the Fiz range on the other. The lake itself is visible from the summit trail, tucked among smaller pools locally called "gouilles" that dot the plateau.

The Carlaveyron nature reserve

The lake lies within the Carlaveyron National Nature Reserve (RNN103), established on 5 March 1991 and covering close to 599 hectares. The reserve is a genuine biodiversity hotspot: surveys have recorded 132 plant species and 460 animal species, including 224 species of insects. The landscape reads like a natural water garden — streams, peat bogs, marshy hollows, and small lakes woven between outcrops and grazing meadows.

What lives around the lake

The reserve's peat bogs host rare plants, among them carnivorous sundew and alpine orchids, while the wetlands support a dragonfly species typical of high-altitude bog habitats. In summer, chamois and Alpine ibex come down to the shores of Lac de l'Aiguillette to drink and to graze on bilberry shrubs nearby. Elsewhere in the reserve, patient observers may also spot lynx, golden eagle, three-toed woodpecker, black grouse, and roe deer, though these are far less commonly seen than the ibex and chamois at the water's edge.

How to reach it

The usual starting points are the Parc de Merlet in Les Houches or the hamlet of La Flatière, at roughly 1,370 m. From there, trails climb past the Bel Lachat refuge (2,152 m) and the Chailloux mountain pastures toward the Carlaveyron plateau, passing in sight of the Bossons Glacier, one of the largest icefalls in Europe. One popular loop that links the lake with the Aiguillette des Houches summit runs about 17.7 km with over 1,300 m of elevation gain — a full day out for fit, experienced hikers. The final push to the summit itself follows an exposed rocky ridge that calls for scrambling with hands; reaching the lake on the plateau below is a considerably gentler proposition.

FAQ

Can you swim in Lac de l'Aiguillette? The lake sits inside a strictly protected nature reserve, so swimming and other disturbances to the ecosystem are discouraged. The point of a visit is to observe the landscape and wildlife, not to use the water for recreation.

How long does it take to reach the lake? It depends on the route and starting point. The approach from Parc de Merlet or La Flatière typically takes several hours one way, and the full loop over the Aiguillette des Houches summit is a whole-day undertaking.

Is the hike suitable for beginners? Getting up to the Carlaveyron plateau is demanding in terms of fitness but technically moderate. Pushing on to the Aiguillette des Houches summit is another matter — the ridge sections are exposed and require a good head for heights.

When is the best time to visit? Summer is the best window, once snow has cleared from the higher stretches of trail and the peat bogs are passable. It's also the season when chamois and ibex are most often seen coming down to drink at the lake.