Marathons can be traced all the way back to ancient Greek when a messenger by the name of Pheidippides ran for several miles from the town of Marathon to Athens in order to announce the defeat of Persia in the Persian-Greco Wars. Today, marathons are now more of a fitness challenge where people push their bodies to the limit. Some, of course, are much more difficult than others, as you will see in this list of the toughest marathons from all over the globe.

1. Everest Marathon

Instead of racing to the top of the world’s tallest peak, the Everest Marathon actually starts at 17,149 feet, and contestants must clear a distance of over 6,000 feet, and cross the finish line at approximately 11,3000 feet. This race is definitely not for the weak as runners are forced to deal with altitude sickness, not to mention the harsh sub-degree weather. The first Everest Marathon was held in 1987 by Tony Hunt and Jan Turner who were inspired by their 12-hour trek up the mountain two years prior.

2. Great Tibetan Marathon

Every year in the northern Indian side of the Tibetan Plateau, runners from across the globe congregate to partake in the Great Tibetan Marathon. Like the Everest Marathon, competitors must deal with insanely high altitudes or in this case, 11,482 feet above sea level. They must also run at a steady pace in order to conserve their low oxygen levels, which is part of the thrill of engaging in such a race. Though before taking off, runners must first acclimate themselves to the high altitude in order to reduce the stress on their body. They can also choose between the half marathon, a 6 mile run, or a full marathon run.

3. Dead Sea Ultra Marathon

On the flipside we have the Dead Sea Ultra Marathon which is held in the lowest place on earth located some 1,312 feet below sea level. Runners must cover an impressive 31 miles, starting at Amman, Jordan then ending at the Dead Sea where they get to experience a significant drop above sea level, some 1,312 feet. Another thing that makes this race unique is that it’s actually a charity event that is held to raise money for neurological patients who can’t afford the costs of surgery.

4. Polar Circle Marathon

The name says it all: the Polar Circle Marathon is literally held at the Polar Circle, more specifically in Greenland. Now you can choose whether you want to run only half the race or the full thing, either way it’s far from a walk in the park. Those who select the former must do so within 4 hours, while the latter is given up to 7 hours. And let’s not forget that you’ll be doing it in 14 °F temperatures. The rugged landscape of gravel and snow certainly adds to the challenge, along with the occasional slippery slopes.

5. Great Wall Marathon

And finally, we’re at the Great Wall Marathon where the goal is to ascend every single one of the Great Wall’s steps and then back down. Now the descent sounds easy, but it’s actually quite steep and so, runners must be extra careful. Like the Polar Circle Marathon, you can choose to do the whole thing or only half, and choosing the latter means that you’ll have to run the Wall just once. As if this wasn’t enough, this marathon also sends participants running through China’s rice fields and villages.