Vallée Blanche: length, vertical drop and conditions of the ski descent

The Vallée Blanche is an off-piste ski route linking the Aiguille du Midi to the Chamonix valley across the Géant glacier, the Tacul glacier and the Mer de Glace. The town of Chamonix classifies it as an unmarked, unsecured off-piste area on crevassed glaciers: no grooming, no markers, no preventive avalanche control. Half a day is enough to ski it from Chamonix, cable car included.

The start is at the summit of the Aiguille du Midi, at 3,842 m, reached by the Compagnie du Mont-Blanc cable car. The classic finish is at Montenvers, at 1,913 m, where the rack railway takes skiers back down to Chamonix. When snow cover is continuous to the bottom, the descent carries on to the valley floor, at the altitude of the Montenvers station in Chamonix, 1,042 m.

The town of Chamonix gives 20 km of descent, 2,000 m of vertical drop and 3 to 4 hours of skiing. That figure matches the Montenvers exit: between 3,842 m and 1,913 m, the descent loses 1,929 m. Carried on down to 1,042 m, it approaches 2,800 m. About one third of the route stays above 3,000 m, and a hut midway allows a break.

The summit ridge of the Aiguille du Midi is descended on foot, skis in hand and roped up, on a ridge the town of Chamonix describes as unequipped. Crampons are essential there, along with harness and rope, and skis go on only once the ridge is behind you. The town of Chamonix makes the route conditional on solid mountaineering knowledge or on being accompanied by a professional. Avalanche transceiver, shovel and probe are part of standard off-piste equipment, as on any unsecured route.

The rope team moves with the rope taut, spaced 10 to 15 m apart depending on its size: about 12 to 15 m for two people according to the ENSA, closer to 10 m for three. Each end of the rope is tied to the harness with a figure-of-eight knot, the middle members with an alpine butterfly or a sling on a friction hitch. Crevasse self-rescue gear, two ice screws, a pulley and a friction-hitch cord, stays accessible on the harness rather than at the bottom of the pack. On steep slopes, when the risk of sliding outweighs the risk of crevasses, spacing is shortened to 1 or 2 m.

A good black-run ski standard is needed, with genuine comfort in variable or powder snow on a glacier. The Compagnie des Guides de Chamonix asks for skiers who handle all snow types on black runs and advises a day of off-piste skiing as preparation. Crevasse positions change with conditions and season: only a high-mountain guide knows the safe line on any given day.

When snow no longer holds down to the valley, the descent ends on the Mer de Glace and the return is by the Montenvers rack railway. The Compagnie du Mont-Blanc gives 5.1 km of track and 871 m of elevation between Montenvers and the Chamonix station, for a journey of about 20 minutes. From the glacier, the gondola station is reached by a staircase: the Compagnie du Mont-Blanc counts about 170 steps between that station and the ice cave, and their number grows as the glacier surface drops.