New pictures have emerged of the harsh conditions being endured by three British explorers in the Arctic trying to reach the North Pole.
The Catlin Arctic Survey team, led by Pen Hadow, is measuring the thickness of the sea-ice.
The group was down to just one day's food rations, in temperatures as low as -40C with wind chill, before vital supplies arrived by plane.
Martin Hartley has been suffering from frostbite and, as he demonstrates, it is a very difficult task trying to dress when your jacket is frozen and your feet are in great pain.
This is part of a series of reports with Pen Hadow on his latest Arctic expedition