In a sport marked by daredevils and radical attitudes, climber Ed Viesturs seems more the Boy Scout.

Although he is the only U.S. climber and one of only five in the world to have scaled the planet's six highest peaks--including a solo on Everest--the 36-year-old Seattle man is as famous for his methodical, ultra-cautious style as he is for his résumé.

That style--from his meticulousness planning to his insistence on waiting days or weeks in base camp for "perfect" summit conditions--is often maddening to less patient partners. But it's clearly one of the reasons for his impressive record.

If Viesturs summits the 26,780-foot Manaslu in the Himalayas this spring, he'll have climbed ten of the world's 14 peaks that exceed 8,000 meters in elevation.

"He's just consistently solid," says Steve Swenson, a Seattle climber and veteran of K2 and Everest. "He's the Cal Ripken of the Himalayas."

Patience will be key this trip. Well before Manaslu, he'll be helping filmmaker and climber David Breashears in the first IMAX film of an Everest climb--a complicated task that entails, among other things, lugging a 45-pound large-format camera package up a 29,028-foot mountain.

Even with seven Everest trips under his harness, Viesturs is awed by the logistics of this project. "Basically, we not only have to run an expedition, but run a film production at the same time."

A native of Illinois, the 5-foot-11, 165-pound Viesturs came relatively late to mountaineering. He is a veterinarian by training, something he had wanted to be from childhood. But after a youthful encounter with books about Antarctic expeditions, he became enamored of the notion of "the struggle, of being completely isolated, totally self-reliant, in a place where you can't just pick up the phone and call for help."

After exhausting his library's cache of explorer stories, Viesturs found on the same shelf a book called Annapurna, Maurice Herzog's gripping record of the 1950 first ascent. After that, he "read every book I could get on mountaineering and decided that I wanted to become a high-altitude climber."

Lacking much in the way of local altitude, Viesturs moved to Washington state in 1977 to attend veterinarian school and learn to climb. He graduated cum laude, got top honors for his surgical skills, and had little trouble landing a job. But he never let up climbing.

In 1982, Viesturs began working as a guide with Rainier Mountaineering, and has taken clients up the 14,410-foot peak 187 times. A glutton for punishment, he competed with other guides to carry the heaviest supply loads from the lodge to high camp. "Load Wars," as they were called, meant a six-hour hike, gaining 4,500 vertical feet, carrying a 90-pound pack. "But it made for a more interesting walk up to camp," Viesturs insists. "And it was great training."

Indeed, the repeated trips, coupled with the huge responsibility for his inexperienced, often painfully slow clients, forced Viesturs to learn patience and honed his already methodical, cautious approach. "You had to be super conservative, always asking yourself 'what if,'" Viesturs says. "You were constantly assessing the situation, always looking down behind you so that you can recognize the route on the way back down."

Yet if Viesturs' climbing approach showed patience, his progression in the sport did not. In 1983 and 1985, he summited Alaska's 20,320-foot Mount McKinley, then in 1987, with no intermediary step, made a bid for Everest, without supplemental oxygen. He and a partner got within 300 feet of the summit before realizing that, although the top was in reach, they lacked the rope for the potentially tricky descent. Retreat was a tough decision, but totally in keeping with the Viesturs by-the-book mode.

"Getting to the summit is optional," he says, sounding a bit like a safety manual. "Getting back down is mandatory."

One consolation of the Everest defeat was Viesturs' discovery that he has an unusual tolerance for altitude. He began to believe that he might duplicate some of the feats of Herzog, Messner, and other alpine legends. He also decided that he would never use oxygen on first attempts, insisting he "wanted to experience the altitude."

Unfortunately, Viesturs also had problems with his employers because of his long climbing vacations. He gave up veterinary work and in 1989, several months after summiting the north face of 28,200-foot Kangchenjunga, he plunged full time into high-altitude mountaineering without any big-name sponsors and only carpentry work for income.

The following year, he climbed Everest, and has mastered at least one 8,000-meter peak every year since. [See résumé].

Two of those expeditions stand out. In 1993, he attempted a solo climb on Everest's north face, making seven bids on the face and two more on the north ridge before bailing due to constant avalanche danger. "I never got high enough to where I was in a position where I could just push myself and go for the summit," he says.

As memorable was K2. On top of funding problems, friction with Russian climbing partners, and horrendous weather, Viesturs and partner Scott Fischer were called upon to rescue a snow-blind French climber. Roped together on the way up, the two had paused on a steep slope at about 24,000 feet, when Viesturs noticed that spindrifts were causing mini-snowslides.

With his ice ax, he began hollowing out a small pit in the slope where he could tuck down in case a larger avalanche began. "I looked up just in time to see Scott engulfed in a slide," Viesturs says. "I jumped in, went into self-arrest, and felt the snow slide over my back." The slide stopped and Viesturs felt a surge of relief--until he realized that the Fischer was still being swept down the hill.

When the 175-pound climber hit the end of the rope, Viesturs absorbed some of the impact, "but his momentum just yanked me out of the hole. We tumbled a few hundred feet before I was able to self-arrest."

Not long after, Viesturs, Fischer, and Colorado alpinist Charley Mace reached the summit of K2. "Ed's just a strong, conservative climber," says Mace. "Where a lot of other climbers would simply plow ahead, Viesturs is always considering the options--and the repercussions--before getting himself out on a limb."

Like other climbers working toward the Big 14, Viesturs has been criticized as a "collector"--a climber who "bags" peaks largely for status and sponsor appeal. And, in fact, Viesturs does not want for publicity or support: He's a constant feature in the climbing press and his current IMAX gig is not only paying his way to Everest (and getting him acclimatized for Manaslu), but guarantees him even greater marketing power.

Still, even cynics have to concede that Viesturs' perseverance at high altitude--where an arctic environment, fatigue, and oxygen deprivation create inhumanly difficult conditions--cannot be explained by mere money or exposure. Rather, Viesturs is an altitude addict, someone who gets off by doing things only a handful of people on the planet could match.

"On summit day, after 10 grueling hours, when you finally get on top and realize that you were focused enough and persevered enough to deal with it, that in itself is its own reward," Viesturs says. "The feeling is totally indescribable."

And, he adds, the view ain't bad either. On his first ascent of Everest, the last leg of which he soloed, Viesturs found perfect weather, light winds, temperature at a relatively balmy 20 below, atop a viewpoint so high that he could see the curvature of the earth.

"I could hardly recognize all the surrounding peaks because from up there, all these huge mountains look like tiny ridges and spires."