Just watching this video will most likely make your knees wobble and your stomach spin.
The remarkable film clip shows superstar rock climber Alex Honnold scaling what could be the most dangerous route in a death-defying sport — with no safety gear.
The fearless (crazy?) American daredevil used nothing but his bare hands, climbing shoes and a bag of chalk dust to conquer El Sendero Luminoso, a route which rises 2,500 feet to the summit of El Toro in El Potrero Chico, Mexico.
El Sendero Luminoso, Spanish for "the Shining Path", is believed to be one of the world's most difficult climbs, rated at 5.12 on the Yosemite Decimal System.
That classification means that "the surface is as smooth as glass and vertical."
Most climbers take two days to complete the climb with ropes and safety gear, but Honnold finished it in just three hours, clinging on by just his fingertips to tiny crevices and bumps for most of the way.
"I would stop at the occasional good foothold and shake it out, but for the most part I kept a very steady pace," he said.
Honnold, who is already hailed as the best climber of his generation, said that El Sendero Luminoso has 'always just represented that next step in technical climbing' to him.
He made his name at the age of 23, when he free climbed Yosemite's Half Dome in just two hours and fifty minutes, an ascent which usually takes between one or two days.
But the Mexico climb is undoubtedly his most impressive feat yet.
Fast forward to 3:01 to really make your palms sweat.