NO ONE SUGGESTS HALEY is reckless in the mountains, not by alpinist standards. But despite his successes, there are a few who worry that his meteoric rise has happened too fast, and that his go-for-it attitude may get him in trouble.

In his immaculately organized gear room, Haley shows me a radical device called a décrocheur fifi, which he's been experimenting with. It's a loose hook that holds a climber's rope to an anchor but falls instantly if he lets his weight off the rope. The advantage: By using this device, a solo climber can leave behind a heavy second rope, and descend a route faster. The drawback: Even a momentary loss of tension on the rope will drop him to his death. "I think there's probably less than 20 people in the world who use this," Haley tells me as his brother Booth looks on. "This is about as sketchy as climbing techniques get." Ominously, as he starts to demonstrate, the hook flings unexpectedly off the wall and clatters onto a bureau.

"You're dead," says Booth. We all share a nervous laugh.

Most of Haley's partners—and most everyone who knows him—say he's uncommonly mature for his age. "He found what he wanted to do early in life, he's sure of himself, and it translated into him being a climber who makes very intelligent and very prudent decisions," says Westman, voicing a sentiment I heard echoed by Garibotti, Cordes, and many others. "Colin has no lack of confidence," Garibotti says, "but I don't see the sign of someone who is throwing himself at climbing in an unprepared manner and is going to have a tragedy. He seems really old for his age."

Still, Haley's off-the-charts motivation puts him in the line of fire more often than others. "I don't want other people to judge him based on second- or third-hand info, but, yeah, I've seen him make decisions that, in hindsight, weren't the best," says House. "I told him that, and he kind of did it anyway. He still has some learning to do."

House and Scott Johnston, 55—who climbed with Haley in Alaska and Pakistan—can recall a handful of examples in which Haley's enthusiasm led him to pick unnecessarily risky routes or eagerly push on in conditions that experienced climbers probably wouldn't have risked.

In one instance, on Mount McKinley in 2005, Johnston and Haley, then 20, were unroped, descending a long runnel of black ice midway through the climb. A TV-size boulder, melted loose by warm temperatures, came ricocheting down the tight gulley, straight at them. They survived thanks to a lucky bounce. Johnston, a longtime guide, recalls having to convince Haley that they were moving too slowly and needed to abort the attempt. "That's when the lightbulb went off for me," Johnston says. "Colin's risk tolerance was way bigger than mine. He would have continued on. I feel like it would not have been a good decision." Haley responds that he was ready to safely continue and that the decision "really had to do with the difference in age and fitness."

There's no question Haley is bold. After Johnston backed out of their plans to climb the Schell Route, on Pakistan's 26,660-foot Nanga Parbat, in 2005, Haley tried to solo it—despite never having attempted an 8,000-meter peak. A little more than halfway up, a storm forced him to retreat. At base camp, House had tried to talk him out of it, to no avail.

"Both Steve and I shook our heads and said this is not a good thing," Johnston says. "We were hoping with Steve's reputation, he'd listen. That was one of those instances where his hubris outweighed his judgment.

"I don't want to denigrate Colin in any way," he adds. "If this guy lives through this, he's going to be an amazing climber. But he is right on the edge where he could be killed at any moment. He's pursuing dangerous alpine problems with the main tool being his unbridled enthusiasm. That's what made me nervous."

Haley sees it differently. "I'm 100 percent just as aware of the risks I take as someone who is much older," he says, "but if I'm going to do hard alpine climbing that has inherent risks, now is the absolute best time in my life to do it."

To some degree, Haley's ambition simply mirrors what is expected in alpinism these days. "To be on the cutting edge now, in 2008, with the first ascents that are left, you've got to hang it out a little bit more than you did 20 years ago, when there were a lot more plums to pick," says Donini.

This summer, Haley and another talented young climber, Canadian Maxime Turgeon, 28, were in Pakistan for an audacious alpine-style attempt on the Ogre, a remote, 23,900-foot cone in the Karakoram Range that's been climbed only twice, and never alpine style. They were shut down by the weather, but their ambition spoke volumes.

"I've said to everyone, the most important thing for Colin is to live through the next ten years," says House. "If he can do that, then look out. Because he's going to have more experience than any of us."