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Free access · June to September
Lac Cornu
High-altitude lake nestled in a wild cirque of the Aiguilles Rouges Nature Reserve, accessible via a mountain trail from the Planpraz cable car.
Guilhem Vellut from Annecy, France · CC BY 2.0 · Wikimedia Commons
At a glance
Type
High mountain lake
Access
Free · No charge
Duration
3h30 round trip from Planpraz (1h30 ascent, 1h30 descent)
Best season
July – mid-September
Parking
Paid (Brévent cable car parking in Chamonix, then Planpraz cable car)
Dogs
Prohibited (Nature Reserve)
Stroller
Not suitable
Town
Chamonix-Mont-Blanc
What is Lac Cornu
Lac Cornu is a high mountain lake located at 2,275 meters altitude in the Aiguilles Rouges massif, in the commune of Chamonix-Mont-Blanc. It lies at the heart of the Aiguilles Rouges National Nature Reserve, in a mineral and wild setting dominated by Aiguille de Charlanon. The lake owes its name to its distinctive crescent shape, visible from Cornu Pass (2,414 m) which overlooks it.
With an area of 5.4 hectares, Lac Cornu is one of the emblematic high-altitude lakes of the Aiguilles Rouges massif, with a maximum depth of 22 meters. The lake is frozen or snow-covered for approximately nine months per year; the summer access period is short, typically from early July to mid-September. Fishing is permitted (Arctic char and lake trout), subject to a license, and the lake offers a peaceful setting facing the Mont-Blanc massif.
Activities
What you can do here
Practical
Practical information
Address
Starting point: Planpraz cable car, 35 Place de la Mer de Glace, 74400 Chamonix-Mont-Blanc View on map
Coordinates
45,936024° N — 6,853158° E View on map
Altitude
2,275 m (lake) · 2,414 m (Cornu Pass)
Opening hours
Accessible from early July to mid-September depending on snow conditions. The lake is frozen or snow-covered for approximately 9 months per year. Check conditions with La Chamoniarde before departing.
Prices
Free access to the lake. Planpraz cable car is paid (round trip required). Prices available on montblancnaturalresort.com.
Parking
Brévent cable car parking in Chamonix (paid). Take the Planpraz cable car (first section of Brévent) up to 2,000 m.
Pets
Dogs prohibited (Aiguilles Rouges National Nature Reserve)
Accessibility
Difficult mountain trail, scree passages, 400 m elevation gain from Planpraz. Not accessible with stroller or wheelchair.
Access duration
3h30 round trip from Planpraz (1h30 ascent, 1h descent, 30 min on site)
Contact
Chamonix-Mont-Blanc Valley Tourist Office: +33 4 50 53 00 24 · La Chamoniarde (hiking conditions): chamoniarde.com
When to visit
When to visit
Lac Cornu is accessible only during the summer season, typically from early July to mid-September. The lake is frozen or snow-covered for the rest of the year (approximately 9 months). The best period is between mid-July and late August, when residual snow has melted and the trail is well clear. In early season (June-early July), snow patches may remain on the trail, making progress more difficult. Morning light (departing early from Planpraz) offers spectacular reflections on the lake. Note: the Planpraz cable car operates on a summer schedule (typically late June to late September) — verify hours before departing and plan to descend before closing (last departure often around 5–6 p.m.).
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Been there? Share your photos — we'll add them to this page with credit. Tag #loisirs74 or email photos@loisirs74.fr
FAQ
Frequently asked questions
Is access to Lac Cornu paid?
No, access to Lac Cornu is free. However, the trail starts from the Planpraz cable car arrival point (2,000 m), which is paid. It is possible to walk up from Chamonix, but this adds approximately 1,000 m of elevation gain.
How do you reach Lac Cornu from Chamonix?
From Chamonix, take the Planpraz cable car (first section of the Brévent cable car) up to 2,000 m altitude. From there, follow the marked trail toward La Flégère, then turn left toward Lac Cornu. Allow 1h30 of walking from Planpraz.
What is the best season to visit Lac Cornu?
The best period for Lac Cornu is mid-July to late August. The lake is frozen or snow-covered for approximately 9 months per year. In early season (June-early July), snow patches may remain on the trail. Check conditions with La Chamoniarde before departing.
Are dogs allowed at Lac Cornu?
No, dogs are not permitted at Lac Cornu because the lake is within the Aiguilles Rouges National Nature Reserve, where domestic animals are prohibited to protect wildlife.
Is Lac Cornu accessible for families with children?
The trail to Lac Cornu is rated difficult (400 m elevation gain from Planpraz, scree passages, mountain trail). It is suitable for children experienced in hiking (from approximately 8-10 years old) and in good physical condition. Not accessible with a stroller.
Can you fish in Lac Cornu?
Yes, fishing is permitted in Lac Cornu, which is home to Arctic char and lake trout. A fishing license is required. Contact the Chamonix Tourist Office for fishing procedures.
Sources
Sources & verification
Multi-source verification at publication date. Information may change — confirm with the official operator before travelling.
