Documenting Alex Honnold's climb

Meet Alex Honnold - at 26 years old, this California native is already a legend in mountain climbing. He practices a kind of climbing called free-soloing and the penalty for error is certain death.

Alex scales rock walls higher than the Empire State building using only his hands and feet. Here, he can be seen climbing the Sentinel in Yosemite National Park - a feat never before attempted without ropes.

Cameraman Peter Mortimer described the challenges of filming Alex's climb, "This is terrifying stuff to shoot because the worst case scenario is you drop something and you affect Alex. The second worst case scenario is you don't get the shot."

To capture Alex free-soloing Sentinel, "60 Minutes" assembled a six-man team of experienced climbers who filmed at different positions along the route.

And, as seen here, cameras - four, in total - were attached to the wall. In addition, two "60 Minutes" teams set up on the valley floor.

This picture shows Alex looking into the lens of one of the cameras that was embedded in a key location on the climb.

Alex prepared for the 1,600-ft. climb by outlining his route beforehand. He climbed Sentinel with ropes and gear twice before his free-soloing attempt and scouted out the best places for his hands and feet.

At five-foot-eleven, Alex is 160 pounds of muscle. And, for someone his size, he has big hands...they have to carry his whole body weight when he's hanging off the rock.

He's completed more than a thousand free-solo climbs - one of the most harrowing was captured in the film, "Alone on the Wall," in which he free-solo climbed the northwest face of Half Dome.

Free-soloing is attempted by less than one percent of people who climb.