From the potential for minus 40-degree temperatures to the armed guards tasked with keeping polar bears from interrupting the competitors, the North Pole Marathon is not your average 26.2-mile race.

Conceived in 2002 by Richard Donovan, a long-distance runner and former economist, the race involves almost 50 participants from all around the world, competing in what is recognized by Guinness World Records as the Northernmost Marathon on Earth. It's also the only race run on frozen water, with some 6-12 feet of ice separating runners from 12,000 feet of Arctic Ocean.

"Anyone who can comfortably complete 26.2 miles on the road can do it at the North Pole," Donovan told the UK Telegraph. "It’s just that they won’t be setting a personal best. The underfoot terrain is very trying. Every step is energy-sapping, like running on sand. Then there’s the cold, and what the wind is doing. That really slows you down."

This year's winner, Argyrios Papathanasopoulos of Greece, ran the course in 4 hours, 34 minutes and 36 seconds.

"Almost unbelievable. You know I’m a Greek guy so this is not the right place for me; it’s like an Eskimo running a race in the desert," he said after winning.

This is race prep like nothing you've ever seen

Putting together the race requires specific timing from several parties, with the Russian military scouting for a solid ice flow on which to hold the event. An air-dropped tractor then clears a runway to allow supplies to be flown in.

Once these pieces are in place, Donovan arrives to map the meandering course, making sure to avoid areas of unstable ice. "It’s not flat," he added. "The ice crashes against itself and creates these little hillocks, some of which are bigger than a person, and I set the course to meander through these features. But everyone needs to stay within binocular range of camp as much as possible because of the risk of polar bears. Fortunately, none has ever come near during a race."

While the competitors won't feel it, the course itself will slowly be drifting underfoot. To best tackle the uneven ground, trail running shoes are the recommended footwear. Despite the harsh conditions, this marathon, like most others, welcomes runners of all levels of fitness.

"Some of the previous participants had never completed a marathon before: determination is the key ingredients to finishing," the official site reads.

Editor's note: This story was originally published in April 2015 and has been updated with new information.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.