North of the Arctic Circle, our Twin Otter soars over the Mackenzie Delta’s maze of waterways and patchwork of tundra, darts across the Beaufort Sea and passes over the British Mountains before shaking and shuddering its way down to Sheep Creek International Airport. Well, that’s what the hand-painted sign says at the end of the grassy wilderness landing area. Parks Canada marks the spot as Imniarvik base camp in Ivvavik National Park, a place that just 100 or so people get to see each year in the extreme northwest corner of the Yukon.