The World’s 10 Hardest Marathons

Iditarod Invitational

Following the 1,000 mile trek of the infamous dog sled races, this race is especially difficult because of the cold conditions rather than the extreme heat you might battle in other races. Prior to being invited to the event, you must complete a 350-mile version of the race one year prior, to prove you can handle the tough conditions.

In addition to racing through snow and ice across the Alaskan tundra, racers are also responsible for bringing their own supplies which can weigh them down in the colder temperatures. It can often take days to reach the next resupply station. To give an idea of the difficulty of this race, in 2014 a record number of just 16 participants finished the race.