Climbing K2 is no easy feat, even under the best of conditions. But going up the “Savage Mountain” without oxygen is an altogether different beast. But that’s exactly what American alpinist Adrian Ballinger did last year, reaching the summit of the second tallest mountain in the world—and arguably the scariest—without supplemental O’s. In this video, he shares some insights into that experience. If you like what you see here, be sure to watch for the second part of the interview coming tomorrow. And of course, don’t forget to watch Adrian’s film Breathtaking K2: The World’s Most Dangerous Mountain.