Chamonix
Haute-Savoie, France




Photos: Tiia Monto (CC BY-SA 3.0), Guilhem Vellut from Annecy, France (CC BY 2.0), Mrvoyage (Public domain), Guilhem Vellut from Annecy, France (CC BY 2.0)
- Distance
- 7 km, La Flégère to Lac Blanc and back
- Climb
- 500 m from La Flégère
- High point
- 2,352 m at Lac Blanc
- Big race
- UTMB, 174 km, usually late August
Why go
Chamonix sits at about 1,035 m under the Mont Blanc massif, and lifts climb straight out of town to balcony paths that run for kilometres above the valley, facing the glaciers. The Ultra-Trail du Mont-Blanc has been based here since 2003, and since 2023 the town has hosted the UTMB World Series finals, so for one week in late August more than 10,000 runners arrive. No other town in Europe has as much mountain running on its doorstep.
The route
The Grand Balcon Sud runs along the sunny side of the valley from Planpraz to La Flégère, mostly above the tree line over pasture, boulders and scree, facing Mont Blanc. From La Flégère, Lac Blanc is 7 km there and back with 500 m of climbing. Across the valley the Grand Balcon Nord runs 5.7 km from Plan de l'Aiguille, the Aiguille du Midi mid-station, to Montenvers above the Mer de Glace, with 523 m of descent.
When to go
The high season is short. In 2026 the tourist office listed the Lac Blanc trail from 1 July to 30 September and the Grand Balcon Nord from 15 June to 31 October, both subject to lifts and snow. The Marathon du Mont-Blanc returns from 24 to 27 June 2027, with registration expected to open between late October and early November 2026. UTMB week ran from 24 to 30 August in 2026; the 2027 dates had not been published by mid-October 2026, and the cycling world championships take over Haute-Savoie from 24 August to 5 September 2027, so the race may move.
Getting there
Geneva airport is 88 km away. Flixbus runs daily from the airport, or take the Léman Express to Saint-Gervais-les-Bains-Le Fayet and change to the Mont-Blanc Express. The guest card from your accommodation gives free train travel between Servoz and Vallorcine.
Permits and booking
No permit is needed to run. Lac Blanc lies in the Aiguilles Rouges nature reserve, where dogs are banned even on a lead, camping is prohibited and nobody may swim in Lac Blanc or the Lacs des Chéserys. UTMB entry needs a valid UTMB Index in the 100K or 100M category and at least one Running Stone, and places go by lottery in January. The 2026 fee was 479 euros.
How hard it is
Lifts do much of the climbing, but these are rocky mountain paths. The tourist office rates the Lac Blanc climb difficult for its gradient, and the steep shortcut down to Montenvers crosses gullies that are dangerous in snow. The full UTMB loop climbs 9,700 m through France, Italy and Switzerland, with a limit of 45 hours 30 minutes.
Where to sleep
Chamonix town has the most beds. The Refuge du Lac Blanc, at the lake, opened from 3 June to 29 September 2026, half board and cash only.
Tips
- Snowfields often linger on high paths in June. Ask the Office de Haute Montagne before going high and carry light crampons after a freeze.
- Book beds and airport transfers early for UTMB week, when demand peaks.



































