You hear about how the Arctic changes people—how it can lead them to lose their minds a little bit, or make dumb mistakes. Then there are those adventurers like Sarah McNair-Landry who are at their best on the ice. McNair-Landry grew up near the Arctic Circle, on Baffin Island. At 18, she joined a skiing expedition to the South Pole. A year later, she became the youngest person to reach both poles. She has since crossed the Greenland ice sheet five times and traversed the Gobi Desert in a kite buggy, among other journeys. Last year, she led a team that towed kayaks 400 miles across Greenland to run a river they'd seen on Google Earth. That was the plan, anyway—but almost nothing went as they expected. Outside contributing editor Florence Williams sat down with McNair-Landry at Mountainfilm, in Telluride, Colorado, to talk about sailing in frozen landscapes, close encounters with polar bears, and where she’s going next.