Honnold told National Geographic that he used a technique called "smearing," which involves placing your foot in such a way that it exerts enough pressure on a smooth rock face to keep a climber vertical. This method doesn't allow a lot of give, meaning climbers must move fast to avoid succumbing to the eventual law of gravity.
"It always feels insecure," climber Joe Kinder said in a tutorial of the technique posted by outdoor equipment sellers Eastern Mountain Sports on YouTube.
Honnold, who trains at a climbing gym in Sacramento, California, when he's not out conquering the world, told National Geographic that he began thinking about taking on El Capitan "years ago," and at first felt it might be too dangerous.
"There were so many little sections where I thought 'Ughh - cringe,' " Honnold said. "But in the years since, I've pushed my comfort zone and made it bigger and bigger until these objectives that seemed totally crazy eventually fell within the realm of the possible."
Honnold's feat earned him accolades from the climbing community, including Emily Harrington, a five-time sport climbing US national champion, who tweeted: "In disbelief out right now. Dude Alex Honnold you're a total hero and also a major freak. Thanks for being both :)"
It's unclear whether Honnold's sponsor, outdoors outfitters The North Face, knew Honnold was attempting the feat, as according to National Geographic, only a "small circle of friends and fellow climbers" knew of his plan. But all's well that ends well, which in free-solo climbing is not a guarantee.
Although no free-solo climber has ever died on El Capitan (perhaps because besides Honnold, it appears no other free-solo climber has tried to ascend it that way), dozens of others have lost their lives in tragic accidents.
One of the most recent such instances came in 2015 when climber Angus Moloney, 22, fell 30m during a free-solo climb of a mountain near Boulder, Colorado.
