Sure, you've got the hang of this sport by now. But can you handle any test it throws at you? What does it take, and how do you get there? Here are 10 defining crucibles, each requiring uncommon ability or training—or both. Some might seem surprisingly accessible (a heliskiing adventure), but others are decidedly extreme (mountain-guiding, teaching your kids to ski). Stand next to these yardsticks and see how you measure up.