The Crossing

Inuvik, 68° North. Every year frost takes a hold of Canada's biggest river, the majestic Mackenzie, making way for one of Canada's longest ice roads and making it possible for isolated Inuvialiut communities to reach each other. But it also allows Canada's only 3000-strong reindeer herd to get to their summer retreat by crossing it while it's still frozen - getting them where the will be protected from predators and will be able to look after their young.