McLEAN, a 44-YEAR-OLD MOP-HAIRED product designer from Park City, Utah, is acknowledged by many as the best steep skier in the United States. "All that crazy-boy extreme-skiing stuff—to me it was all just a Mountain Dew ad," says Himalayan climber Conrad Anker, 42, who has teamed with McLean on several climbing-and-skiing expeditions. "It was never the real thing. Except for Andrew."

Because McLean declines to appear in extreme-skiing videos—he's frequently asked to—and doesn't endorse a signature line of skis (though K2 Skis sponsors him), he remains largely unknown to the general public. But among backcountry cognoscenti, his name is legendary. He's perhaps best known for researching and writing The Chuting Gallery: A Guide to Steep Skiing in the Wasatch Mountains, a backcountry handbook that McLean self-published in 1998. These days, used copies of this collector's item fetch nearly $200 on Amazon.com, though it's clearly not for everybody. Essentially a guide to avalanche chutes identified by the Utah Department of Transportation, it tells you where to find barely skiable lines that can easily lead to fatal accidents—a fact the author acknowledges with a low-key warning in the introduction.

"Much of this book is written in a flippant manner that at times can glamorize and/or downplay the dangers involved in this type of skiing," McLean writes. "In truth, it's not a very safe activity."

Risks notwithstanding, in the past decade no athlete has pushed the bounds of what's possible more than McLean. He's done it by taking skis where they've never gone before and by creating new tools that allow him to go there. On remote slopes in the Wasatch, the Cascades, the Rockies, and the White Mountains, skiers tell tales of McLean's descents on Alaska's Mount McKinley and Mount Hunter, of the turns he carved down Mount Rainier's forbidding Mowich Face, of the 3,500-foot chutes he discovered—and skied—on Canada's isolated Baffin Island.

"They say McLean skis what the rest of us ice-climb," says veteran backcountry skier and photographer Carl Skoog. "I don't know if that's true, but . . ."

It's true. It's also true that, during the nineties, while working as a product designer for Black Diamond Equipment—a cutting-edge backcountry-gear company based in Salt Lake—McLean invented a number of devices that helped define the wild new junction where skiing and mountaineering converge. The HotWire, a lightweight wire-gate carabiner he created in 1994, drastically reduced the problem of catastrophic failure due to gate opening and represented the first advance in 'biner design in a generation. The Whippet, a ski-pole grip with an ice-ax head that McLean invented in 1995, has become standard issue for aspiring and veteran ski mountaineers. His latest project, a series of ski-kites, isn't in commercial production and may never be, but there's a growing demand for McLean's prototypes among climbers and skiers heading to the polar regions. As it happens, McLean is also at an interesting junction in his own life. He recently got married to Polly Samuels, an assistant attorney general for the state of Utah and a skilled backcountry skier. After the ceremony, at Alta's Our Lady of the Snows Chapel, the newlyweds emerged under an archway of crossed ski poles. The couple—reserved but hardly reclusive—even had their nuptials featured in The New York Times.

Marriage is the point where many adventurers try to cash in on their accomplishments, but McLean, ever the iconoclast, has decided to cash out. In 2003 he left his job at Black Diamond—amicably—so that he could have more time to ski, futz with gear, and take off on far-flung expeditions, a move that has upped his freedom but curtailed his cash flow. Now at an age when intelligence, experience, ambition, and ability all meet, he's working on his boldest innovation yet: an unfettered lifestyle that will support his yen for adventure skiing and give him a chance to stage a second act as impressive as his first.

Of late, McLean's passion has extended into the development and promotion of ski-mountaineering racing—a fledgling sport in the U.S. that's already hugely popular in Europe. These races require competitors to climb and descend steep, sometimes dodgy off-piste terrain using climbing skins and lightweight alpine-touring skis, boots, and bindings. Until recently a top-flight racer himself, McLean has retired his bib to help boost the sport stateside, luring enthusiasts and hardcore endurance athletes to the events. His own race, the Black Diamond PowderKeg, created in 2003 and held every March in the Cottonwood Canyons, is the first Ski Mountaineering World Cup event in the U.S, part of a growing international series similar to the one that defines alpine ski racing.

The growth of these races illustrates the ongoing boom in backcountry skiing. In 2001, the Jackson Hole, Wyoming–based gear company Life-Link/Dynafit sponsored its first race. In 2005, they held four races, and total participation had quadrupled. "We could have run ten races this year," says John Scott, Life-Link's executive vice president. "But we had to turn areas down because we just didn't have the time to do it." At this pace, the sport could soon become as popular as mountain-bike racing or halfpipe competitions.

Though McLean would never claim all the credit for popularizing the winter backcountry, his impact is undeniable. While much of what he does takes place at the bleeding edge, he's opening the gap between old ways and new, inspiring others to push beyond resort boundaries. In the McLeanian imagination, snow-covered mountains are places of unlimited opportunity. And when it comes to figuring out how to have fun there, he's just getting started.