BERKELEY, Calif. -- It might be hard to conceive of now, in an era of extreme sports and ultra-light equipment, but there was a time when Americans who set out to conquer mountains engaged in a pursuit that was as lonely as it was dangerous.But four men -- Norm Dyhrenfurth, 94, Jim Whittaker, 84, Tom Hornbein, 82, and Dave Dingman, 76 -- remember. The leather boots that stayed wet for weeks. Oxygen canisters that weighed 15 pounds. The shrugs of indifference their countrymen gave a half-century ago to what it would take to get a U.S.-led mountaineering expedition to the top of Mount Everest."Americans, when I first raised it, they said, 'Well, Everest, it's been done. Why do it again?'" Dyhrenfurth recalled recently as he and three other members of the 1963 expedition gathered in the San Francisco Bay area for a meeting honoring the 50th anniversary of their achievement.Their feat, captured in a Life magazine cover story, came to represent, in the years after President John F. Kennedy honored the Everest team, the birth of mountaineering as a popular sport in the U.S."When they were talking about a reunion three years ago, I thought, who the hell cares about that? I figured we'd just get together for some beers," Dingman said between interviews with National Geographic, Outside magazine and the Alpine Club's oral history project. "It's turned into this big event, and I'm glad it has."Whittaker, who lives in Seattle and went on to become chief executive of outdoors outfitter Recreational Equipment Inc., was the first American to summit Everest. He and his Sherpa companion, Nawang Gombu, reached the top of the world on May 1, 1963, a decade after Great Britain's Edmund Hillary and about six weeks after Jake Breitenbach, a climber on the U.S. expedition, died in an avalanche.Memories of how close Whittaker came to dying on Everest -- he and Gombu ran out of oxygen on the summit and had to climb up and back without water after their bottles froze -- infused every day of his life since with gratitude and childlike wonder, he said."I think I will probably take it with me into my next life, if I have one," Whittaker said.Three weeks after Whittaker's ascent, two other Americans, Hornbein and the late Willi Unsoeld, became the first men to scale Everest via a more dangerous route on the mountain's west side. The next day, they descended by the southern route that Hillary, Whittaker and, by then, two more members of the American team had taken to the summit.The adventure, which included spending the night without sleeping bags or tents at 28,000 feet, made them the first men to traverse the world's highest peak -- and cost Unsoeld nine frost-bitten toes.