A freak swell that creates a towering wave in Tahiti and a rare rolling cloud that looms dangerously in the skies above Australia are irresistible lures for athletes to confront these natural wonders.

Bernhard Witz and co reach the top of Angel Falls in Venezuela, the highest waterfall in the world. But illness threatens their plan to traverse a highline suspended 2,625 feet above the jungle.

The Wrangell Mountains in Alaska may be out of bounds for helicopters, but they won’t stop legendary freeride snowboarder Jeremy Jones. He ventures by foot to find the fastest route down.

Using sophisticated technology to hunt fearsome storms that create monster-sized swells, veteran surfers Ross Clarke-Jones and Tom Carroll set off for the unridden waves of Pedra Branca.

French duo Tancrède Melet and Julien Millot are masters of highlining. Untethered and thousands of metres above sea level, they BASE jump into the void, synthesizing a new sport they call BASE Lining.

Most people's nightmares are a dream come true for Jeb Corliss, a world-class BASE jumper whose surreal flights nearly end when he gets too close for comfort to South Africa's Table Top Mountain.