Inspired by an infamous assassin's escape from prison, the Barkley Marathons just might be the toughest race on the planet: a 100-mile-long, unsupported slog through the Tennessee backcountry that only 14 people have ever finished. Madison Kahn spoke to three of the event's regulars to get the story behind the Barkley.

Using Twitter and a lot of hugs, a renegade tribe from Boston attempts to reimagine fitness as a social event

How research supports the therapeutic benefits of playing outside

We’ve all got that buddy—the one who executes an epic ski or raft mission every year. Reader Keith Pearen is one of those guys. For the past 10 years, the 32-year-old Boulder, Colorado, aerospace engineer has been organizing trips for groups of up to 20 friends. Here’s the formula he applies.

This month marks 25 years of amazing footage, corny hosts, and fake blood for the Discovery Channel’s most-watched series

Quadruple amputee Philippe Croizon takes on some of the boldest open-water crossings of all time

The latest gadgets collect reams of training data. Here are the metrics that matter.

From sharks and cougars to avalanches and frozen waters, four survivors share their stories in their own words. Plus: expert commentary.

A running monitor that turns any workout into a game and collects information on your every move

All you need to know about going wild with man's best friend, including training tips, canine gear, and wilderness etiquette

Catching up with the Kiwi kayaker between races about his upcoming debut at the London Olympics; his girlfriend, Martina Wegman; and how he tries to close the gap between slalom kayakers and creek boaters

For the past 12 years, Middaugh, a seven-time X-Terra National tri champ with seven more events on his schedule for this summer, hasn't gone more than a month without competing

Ric Gillespie has spent the past three decades looking for what he calls an “any-idiot artifact”: a bombproof discovery that will persuade the world he’s found Earhart’s crash site. Here are TIGHAR’s greatest whiffs.

Ignore what you've been told: Summer is the time to try something new

Red Bull marketing copy or Lord of the Rings?

Celebrity nature-doc narrators get graded

An abridged history of waterproof-breathable warfare

Can Caroline Queen win a gold medal at the 2012 Olympics?

A new body surfing doc goes to Tahiti, New Zealand, and Hawaii to tell the story of wave riding's most basic discipline

The pro skier talks avalanche safety

Alone in a vast Alaskan wilderness, seven teens fend off a grizzly bear—then try to stay alive

First energy drinks came in skinny cans. Then it was dissolvable packets. Now they're available in inhalable powder form.

Cognitive scientists are only just beginning to understand what being in nature does for our mental health. But—big surprise!—the evidence is promising. Here are five smart reasons to go wild.