What makes for true adventure? We asked legendary mountaineer Reinhold Messner.

“Climbing for me is more than a sport,” writes mountaineering legend Reinhold Messner in his book, My Life at the Limit. “Climbing is all about freedom, the freedom to go beyond all the rules and take a chance, to experience something new, to gain insight into human nature… For me, imagination is more important in climbing than muscle or daredevil antics.”

Indeed, Messner has a decades-long laundry list of achievements. In the 1960s while he was still a teenager, he made groundbreaking 5.10 free solos on the rock walls of his native mountains, the Dolomites. In the 70s and 80s, he achieved legendary solos and oxygen-less, alpine-style ascents on the 8,000-meter giants of the Himalaya and the Karakoram. Then throughout the 90s in the twilight of his adventuring career, he completed remarkable and often overlooked long-distance crossings of Greenland, the Gobi Desert, and Antarctica. It’s easy to be so swept away by the empirical proportions of his success that one misses the determination and sense of artistry that were driving him. For all practical purposes, we’re talking about a guy who was elite rock climber Alex Honnold as an adolescent, then became speed alpinist Ueli Steck in his 20s, then morphed into 8,000-meter man Ed Viesturs and finally polar explorer Earnest Shackleton in his later years.

Messner now seems to have comfortably settled into a final role in his career—that of communicator. In Europe, he’s spent more than a decade building a series of museums devoted to human interactions with mountains. On a recent trip to New York City to deliver the keynote address at the American Alpine Club annual dinner events, I had the opportunity to interview him for National Geographic Adventure. (See our video with climbers Tommy Caldwell and Kevin Jorgeson on life after the Dawn Wall first ascent.)

Clearly, Messner knows a thing or two about mountains—and how to survive them. What was interesting to me was how he spoke of his greatest feats—climbing Everest without supplemental oxygen, for instance—as a general exercise in creative problem solving. “It starts with an idea,” he says, “and the idea becomes a vision.”

In the 21st century, it is painfully obvious that genuine exploration is an endeavor of finite geographic proportions— there’s no way to turn back the clock and re-discover the route to the summit of Everest, for instance. Reinhold Messner is apt to remain the greatest high-altitude mountaineer of all time simply because he had the good fortune to come along at precisely the right moment in history, when the world’s tallest mountains were ready to be challenged on their own terms. This fact is something Messner himself is acutely aware of—and it helps explains why he periodically changed directions over the course of his life.

“Adventure has to do with private, personal experiences,” Messner says. “But, the possibilities, there are millions of unclimbed mountains—I have seen in the Eastern part of Tibet, mountains 6,000–6,500 meters high, vertical walls twice as tall as the Eiger… but nobody is going there, because they aren’t 8,000-meter peaks.”