Lac Cornu & the Aiguilles Rouges Nature Reserve
While the crowds queue for the Aiguille du Midi, a handful of walkers slip across the valley to the Aiguilles Rouges — the rust-red ridge that faces Mont Blanc from the north. Up here, at around 2,200 metres, a chain of glacial tarns including the deep-turquoise Lac Cornu reflects the entire Mont Blanc massif in near-perfect silence.
The Hike to Lac Cornu
Take the Brévent cable car from Chamonix to the Planpraz mid-station (2,000 m), then follow the GR Tour du Mont Blanc westward for about 45 minutes on a well-maintained trail through rhododendron scrub and granite boulders to reach Lac Cornu. The lake sits in a natural granite bowl and its colour shifts from jade green to cobalt blue depending on the angle of the sun.
Continue another 20 minutes above Lac Cornu to the smaller Lacs Noirs for an even more remote feel. On a clear morning in July or August the reflection of the Aiguille Verte and Les Drus in the still water is one of the great unsung photographs in the Alps.
Wildlife & Wildflowers
The Réserve Naturelle des Aiguilles Rouges, established in 1974, protects 3,300 hectares of high alpine terrain. Marmots whistle from every boulder field, ibex are regularly spotted on the ridge above the lakes, and in late June the meadows below Planpraz explode with alpine roses (Rhododendron ferrugineum), gentians and Martagon lilies.
The reserve's small visitor centre at the Col des Montets (1,461 m), accessible by car on the N506 road toward Argentière, has excellent free exhibits on the glacial geology and endemic flora of the massif — worth 30 minutes of your time.
Practical Notes
The Brévent cable car (téléphérique du Brévent) departs from the west side of Chamonix town; a return ticket to Planpraz costs around €22. The trail to Lac Cornu is straightforward in good conditions but requires proper hiking boots — the granite slabs are slippery when wet.
Go on a weekday morning in July or August for the best chance of solitude. Bring a picnic: there are no refreshment facilities beyond Planpraz's small café. Swim in Lac Cornu if you dare — it is glacier-fed and stays below 12 °C all summer.
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