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    Lac Cornu

    This reflects the 10Adventures difficulty rating for each route. We aim to keep ratings consistent across regions.
    This reflects the estimated time the majority of users will take on this trail. If you are slower, add time to the top-end figure. If you are fast, then you may complete this route faster than this time range.
    This reflects the return distance of this route as measured by the GPS file.
    8.5 km
    This reflects the total elevation gained throughout this route as measured by the GPS file. This includes all ascents and descents, and is higher than what is quoted in most route guides, which simply measure the distance between the starting-point and high-point of the route.
    651 m
    User Ratings
    These ratings are completed by users who have completed this trail and not subject to reviews by 10Adventures.
    Overall Rating
    This is the average user-submitted overall rating on a scale of 1 to 10, with 10 being the highest.
    Physical Difficulty
    This is the average user-submitted rating on the physical difficulty of this route. In general, green is beginner, blue is intermediate, black is advanced/most difficult and double-black is expert-only. It is recommended that users build up to black and double-black routes.
    Intermediate (Square)
    Suitable for intermediates who are ready for a little bit more adventure.
    Technical Difficulty
    This is the average user-submitted rating on the technical difficulty of this route. In general, green is beginner, blue is intermediate, black is advanced/most difficult and double-black is expert-only. It is recommended that users build up to black and double-black routes.
    Easy (Circle)
    Suitable for beginners, families, young children, and those looking for a casual adventure.
    Read Reviews
    Directions to Trailhead
    Panorama of the Lac Cornu hike near Chamonix, France

    The Lac Cornu Hike takes you away from Chamonix valley’s villages and lift systems for a higher, wilder, and quieter hike. Climb to a col looking across at the Mer de Glace and the Drus. Slip behind a ridge and down to three mountain lakes overlooking the Rochers des Fiz. Hike back into the Chamonix valley, and finish at Planpraz for a perfect Mont Blanc view.

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    Route Description for Lac Cornu

    The hike to Lac Cornu and Lacs Noirs uses lifts. When buying your tickets at the Téléphérique de La Flégère cable car station, explain your planned itinerary (Lac Cornu from the Index lift, walking down to PlanPraz mid-station) as it’s best to check with the staff at the lift station to confirm that the path is accessible. They may suggest a different route according to conditions.

    The hike to Lac Cornu starts at the top of the Index lift. From here, take the wide ski trail towards the Col de la Glière. After about 15 minutes, there’s a right-hand turn, clearly signed to Col de la Glière.

    The trail takes you across a wide, sweeping bowl, through an area of scree, and then heads upwards in a series of long hairpin bends to the col. There’s a short, exposed section over a narrow rock ledge - a strong cable provides a grip here.

    At the Col de la Glière (2,461 m), get your breath back and admire the panorama in which the Aiguille Verte is particularly spectacular, rising directly in front of you.

    The col has signposts to the two lake areas and they are both well worth exploring. You’ll see Lac Cornu below to your left. But to start follow the sign and the yellow paint markings to Lacs Noirs. Once at the first Lac Noir, it’s fun to explore around the rock shore, admiring the view from different angles before following the yellow splashes on to the second Lac Noir. Depending on the time of year, there may be snow here.

    To get to Lac Cornu, retrace the yellow marks to the Col de la Glière and take the path signed to Planpraz and Lac Cornu. The next section is an interesting hike, as you walk and hop over gigantic boulders - it’s well marked and fun to do!

    After half an hour, you’ll arrive at the cairn marking the Col du Lac Cornu. Take in the dramatic faces of the Rochers des Fiz on one side, and the majestic view of Mont Blanc and its surrounding peaks on the other. Here, you can see Lac Cornu, a very pretty spot, often fringed with flowers, tucked in amongst the rocks below. Turn right and hike down to Lac Cornu. This is ideal for a picnic and cooling your toes in the cool water.

    After your break at Lac Cornu, return to the Col du Lac Cornu and follow the path signed to Planpraz. This is a clear and easy hike that leads you through juniper, rhododendron and blueberry bushes, eventually going below the Col du Brévent. Follow the path back to the PlanPraz lift and take it back down into Chamonix.

    Insider Hints for Lac Cornu

    • Snow can linger at the Col de la Glière well into July - check at the lift stations or Maison de Montagne if you do this walk in early season. If the snow looks dangerous at the col, do not hesitate to turn back.
    • This hike can be done equally well in reverse from Brévent - it’s well signed in this direction too.
    • For a (very) big day’s walk, and one of the best walks in the Alps in our opinion, combine this walk with the Grand Balcon Sud.
    • Dogs are not allowed on this walk.
    • Roll back down the hill from Brévent and finish off with a well deserved apero and snack at Cool Cats in the Rue des Moulins - artisanal hot dogs and live music on early summer evenings.

    Getting to the Lac Cornu Trailhead

    Take the Téléphérique de La Flégère lift from Les Praz de Chamonix, a village North of central Chamonix. You will then take the L’Index chairlift from the top of La Flégère.

    Route Information

    • When to do

      Mid July - Mid September

    • Backcountry Campsites

      No. Bivouac permitted sunset to sunrise.

    • Toilets

      At Flegere and Plan Praz

    • Family friendly


    • Route Signage


    • Crowd Levels


    • Route Type

      One Way

    Lac Cornu Elevation Graph

    Weather Forecast

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    Lac Cornu Reviews

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