
Adventurers seek new and extreme challenges.

Onekotan is a Pacific island with a collapsed volcano that Matthias Haunholder wants to ski down.

Jon Durand has dared loop-the-loop aerobatics on the leading edge of the Morning Glory, a rarely spotted, two kilometer-high tube cloud phenomenon.

If Troy Watson and Kieran McKay can connect New Zealand's Nettlebed and Stormy Pot systems, the find will be the biggest cave in the Southern Hemisphere.