Highs and lows of Arctic trekking

Polar explorers Pen Hadow, Ann Daniels and Martin Hartley are nearing the end of an epic trek across the Arctic.

They have been taking measurements of sea-ice thickness - primarily from drilling following the failure of a mobile radar unit - in a bid to help scientists better understand the changes taking place at the highest latitudes.

The team has not only had to suffer the harsh Arctic elements, but has also been besieged by technical failures and delays.

And the explorers are now being picked up much early than originally anticipated - thanks, in part, to the rapid ice melt.

Here they describe their highs and lows.