A ropeless climb 2,000 ft. up the vertical side of Yosemite's Half Dome is nerve-racking just to watch. Doing it is unfathomable. But this is the sport of "free soloing," and its champion is Alex Honnold, 26, who has set speed records on this and other extreme routes by lifting himself on chalked, calloused hands and size-12 feet wedged into crevasses-foregoing the fail-safe of ropes, a parachute or a partner. "If I actually think I'm in danger, I don't think I'd go for it," says Honnold, a Sacramento native known to would-be peers as "Alex-No-Big-Deal." Says climber Tommy Cadwell: "He can block out fear, which makes for some pretty spectacular things." Honnold, who often climbs with ropes first to map a route, can't block out everyone's fear, however. "I had to get over being scared," says his mom, Dierdre. "It's all he loves."