Trekkers and climbers disembark from the vintage Russian MI-8 helicopter on the airstrip at Lukla to begin the 10 day walk to Mount Everest. Photo by Peter Potterfield

Camp on Mount Rainier's Carbon Glacier, with Liberty Ridge rising to the summit behind. Photo by Peter Potterfield

Climbing in Diablo Canyon, New Mexico, 1977. Photo by Ray Sena, Peter Potterfield collection

A climber moves through the solitary vastness of the Sera Peaks, Tellot Glacier, British Columbia. Photo by Peter Potterfield

After two days of rain, a clearing storm lets a setting sun illuminate the wild backcountry of Rainier's Northern Loop Trail. Photo by Peter Potterfield

Descending Trident Ridge toward the Crean Glacier on South Georgia Island. Antarctic Bay is on the left. Ernest Shackleton called the peak at the pass "the Great Nunatak." Photo by Peter Potterfield

Mike McClelland brings the big Bell 212 in to retrieve a group of hikers from Crystal Peak in the Cariboo Range of British Columbia. Photo by Peter Potterfield

An autumn hiker makes an early start for home in the west side backcountry below Mount Rainier's Sunset Amphitheater. Photo by Peter Potterfield

Jim Nelson sets off on another lead in typical conditions somewhere in the Coast Range. Photo by Peter Potterfield

Gazing out to the peaks of the High Sierra's Upper Kern Canyon while doing a cross-country route from Southfork Pass to Dusy Basin. Photo by Peter Potterfield

Climbing in the Coast Range of British Columbia, one of the wildest mountain ranges on the continent. Photo by Jim Nelson, Peter Potterfield collection

The author belays Scott Fischer, in the red jacket, as Fischer offers encouragement to a rope team trying to retrieve a member from a crevasse at 12,000 feet on Mount Rainier, 1986. Photo by Peter Potterfield

On a solo hike through the wilds of the Swedish Arctic, perhaps the most interesting backcountry travel in Europe, the author found such solitude the only way to take a photo of a hiker was to put the camera on a rock and set the timer. Photo by Peter Potterfield

The surprising expanse of Ruth Amphitheater in the Alaska Range. Photo by Peter Potterfield

James Martin, photographer, at work on the Paria Plateau. Photo by Peter Potterfield