Top 5 Toughest Marathons in the World

North Pole Marathon:

From extreme heat to extreme cold

If you thought running in the blistering heat was mad enough, this marathon takes it to a whole new level of crazy. Running in subzero temperatures requires a LOT of stamina and a strong heart.

The runners do 10 laps around the North Pole in a 2.6-mile radius before crossing the finish line close to the base camp.

If that is not dangerous enough, the other thing they need to be careful about is falling afoul of the local wildlife, namely polar bears which can easily outrun a human, but fortunately the organizers come armed in case of such an occurrence.