So, feeling like a plunge down a Himalayan river, a race up the face of a Patagonian spire, or a ski expedition to the North (or South—that's O.K. too) Pole? Feeling a little scared? That's why we call them Tough Trips.

The Tough Trips Guide Mountaineering Patagonia Alaska Bolivia Wildwater Paddling Bhutan Greenland California Trekking Peru India Canada New Zealand Ski Mountaineering The Tetons British Columbia Maine Expedition Biking China The Continental Divide Polar Exploration The North Pole The South Pole

As for the rest of us, let's be honest. Hard-core adventureis something we've merely brushed up against in the course of shorter, less exacting voyages. Such journeys are bracing, but they won't revolutionize your life. For that, you need to push yourself a step or two beyond what you thought you could do—and then push a little farther. You need to go through the kinds of trials that produce what climbers call the North Wall Look:the stare that says you've been to the edge and survived. In other words, you need to take a Tough Trip.

Tough Trips require months of training, research, and discipline—and then they pay you back with hardship, sore muscles, and second thoughts. But somewhere along the way—say, after you've ascended Denali's West Rib or skied the face of the Grand Teton—you may catch a glimmer of the sublime.

To give you a sense of the options laid out before you on this less-traveled road, and to help you tackle some key questions (Guide or no guide? Will I need a satellite phone? What, exactly, do the words "forbidden zone" mean?) we've assembled the hardest adventures we could find and tapped the brains of a few of our favorite writers who have been there and back. These journeys span the globe, so get out your atlas. And remember, going the distance is only half the fun. The other half isn't so much about the sacrifices or the miseries you endure, but the sense of having touched something so far out in the world, and yet so deep in your core, that you can't wait to get out there and do it all over again.