A good climb from either Italy or Switzerland, the summit crest is usually the main difficulty – conditions on this section dictate the safe guiding ratio.

Castor can be climbed from the guides D’Ayas or Quintino Sella huts, or even from Zermatt in a day if you like to go quickly. Either route involves a glacier climb followed by the final snow crest. It’s also possible to traverse the mountain from one hut to the other, or combine it with the ascent of other nearby summits such as the Breithorn or Pollux.