Sometimes you need to ski with a harness. There are gaping crevasses, seracs, and bergschrunds around every turn in Chamonix, so you’ll want a harness and a rope for rescue purposes. If you’re skiing in glaciated terrain—like Chamonix’s Vallee Blanche, a 10-mile off-piste glacial run off the Mont Blanc—go with a guide (hire a good one at www.chamonixskiguide.com). You can rent a harness from your guide, or bring Black Diamond’s Couloir Harness [$50], which is lightweight and packs into a ball the size of a soup can.