This jaw-dropping 2800m descent is the ride of a lifetime and probably Europe's most famous off-piste experience. Beginning at the Aiguille du Midi, the 20km route darts over the crevasse-riddled Mer de Glace glacier and returns to Chamonix through the forest. Skiers must be confident on red pistes and in good physical shape; the reward is access to a landscape of eerie, unearthly beauty. The route can only be tackled with a guide de haute montagne (specially trained mountain guide).
The tourist office has a list of guides, or ask at the Compagnie des Guides.