In search of a new challenge, Swiss mountain climber Ueli Steck gets into peak condition to break the speed-climbing record for the three most notorious northward faces in the Alps: the Eiger, the Grandes Jorasses and the Matterhorn.

BASE jumper Karina Hollekim risks an extreme 600m jump from Hand of Fatima in the Malian desert.

South African kayaker and adventurer Steve Fisher plans one of the riskiest projects of his career: navigating the narrow canyons of the Zambezi river below the Victoria Falls during one of the most extreme high-water periods in history.

The Oceans Seven are the seven most treacherous ocean channels in the world to swim across. No human has ever done it, but Irish marathon swimmer Stephen Redmond has conquered six. Now he hopes Tsugaru Channel in Japan will be his grand finale.

In 2011, Thomas and Alexander Huber with Mario Walder were the first climbers to attempt a redpoint team free ascent of Mount Asgard on Baffin Island, Canada. After 28 pitches, the three climbers stood atop its South Tower.

On every new and full moon, an enormous tidal wave occurs along the lower Amazon. It's a tempting target for surfers despite the wave power, water hazards and isolation that make it dangerous, but a team of pro big-wave surfers accept the challenge.