It is one of the world's most remote and unforgiving environments. Yet a handful of people are determined not just to reach the North pole - but to run 40 kilometeres there.
Its the world's most northerly sporting event and the only marathon run entirely on water taking place during a period of 24-hour sunshine when the arctic region is entirely frozen.
Competitors are forced to undergo an arduous training and acclimatisation programme. Finding a location to train for such a challenge is a challenge in itself and Britain's Ted Jackson took the unusual step of running in the freezer at his local butchers.
It is a quest that produced emotions as extreme as the landscape.
In a special programme Sportsworld's Andy Richardson went behind the scenes to join the participants on their journey to the top of the world.
Watch part one of this episode of Sportsworld on YouTube
Watch part two of this episode of Sportsworld on YouTube
This Sportsworld special aired on 07 April and will be broadcast at the following times:
Monday: 1130 and 2030, GMT Tuesday: 0230 and 0730 GMT, Wednesday: 1330 GMT, Thuesday" 0630 and 1930 GMT, Friday: 0130 GMT
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