Video: Runners take part in North Pole Marathon
The North Pole Marathon kicked off with a temperature of -30° Degrees Celsius.
47 competitors from 20 countries pitted themselves against the elements for this race at the top of the world.
The event took place at Russia's Barneo Ice Station in the Geographic North Pole.
The race is literally run on water: the difference is that it's Arctic sea ice.
The course is the standard distance 42.2-kilometre (26.2 miles) marathon, and attracts a range of runners from military personnel to experienced marathon and ultramarathon runners - and those making their marathon debut at the top of the world.
Competitors must negotiate soft snow in addition to the sub-zero temperatures.
Mainly for safety reasons the course is laid out around the Russian camp, with markers positioned in the snow and ice.
Competitors have to complete 12 laps of the course but are able to retreat into a refreshment tent to regain body warmth - and hydrate themselves with hot drinks and snacks.
Some also take the opportunity to add or remove layers of clothing that protect them from the harsh elements.
Course marshals and timekeepers scrutinise the race while guards patrol with guns, to frighten off any polar bears who might be feeling peckish and fancy a bit of runner.
USA's Mike Wardian was first home in an impressive time of four hours, seven minutes and 40 seconds (4:07:40).
The American Ultra runner led the race from the start.
He was never really troubled despite temperatures dipping below -30° at times - but nevertheless described it as the toughest race he's ever run.
Second place went to British runner Luke Wigman, who finished the race 57 minutes later.
Germany's Anne-Marie Flammersfeld won the women's event in a time of 4:52.45.
She was second in the whole field and set an all-time record for the ladies' event.
This year the majority of competitors finished the race, although some took a majestic 10 hours to do so.