Needs a full day from the Aiguille du Midi cable car. From the cable car station you take a path - dangerous when covered by ice - to the glacier located 300 m below. That's the starting point of the piste leading down through the Vallée Blance and Mer de Glace. The easiest route can be skiied by someone who is confident on red runs, although a guide is highly recommended due to the glacier on which you would be skiing. This is not something to attempt in bad weather.