In tonight's episode, both teams face their toughest challenge yet. As part of their route, both teams must move through the Mount Forel range, navigating their way through two crevasse-ridden glaciers. For Bruce Parry and his team, it is not only an immense physical challenge, but with the team's dogs still misbehaving it is also incredibly dangerous. If and when they make it through the glaciers, both teams then have to brave it through the plummeting temperatures of the ice cap.