This extreme sport is fundamentally like mountain climbing…only really slippery. Ice climbing requires strong arms and legs to hoist your body up a slippery slope. But that's just one aspect of the sport. "We emphasize intelligence and technique rather than brute strength when ice climbing," says Mike Hardert, director and senior guide for the International Mountain Climbing School in North Conway, New Hampshire. "And it helps to have really good balance." One hour of ice climbing burns about 700 calories!