In 2006, Larsen completed an audacious 62-day expedition to the North Pole to cast a spotlight on the melting Arctic. "It was crazy hard," says the 45-year-old, who had to drag a 250-pound sled for 550 miles. "And for a big part of the trip, it was too remote to be rescued — that adds a huge level of severity." He followed that up in 2009 by becoming the first person to tag the North and South Poles and to summit Everest within a single year. But the pinnacle of Larsen's adventuring came in 2014 when he made what could be the last journey from land to the North Pole, a 480-mile trek over shifting ice in 53 days. "There are plenty of people who do polar work, but they don't last long," says legendary explorer Will Steger. "Eric started young and is now one of the most accomplished — and he's our witness to the melting ice."