These Are Six of the Most Challenging Ultramarathons on Earth

Running hundreds of miles may seem like an impossible task. However, when a runner begins training, the notion of running a 5K or 10k may seem like an impossible feat of endurance. For runners who have broken the marathon barrier, ultramarathons are the ultimate test, pushing their limits to Herculean limits. Humans love to rise to a challenge. As athletes hone their skills and become more fit, what once seemed an insurmountable goal becomes easier, inspiring them to keep raising the bar, running faster and further than before.

Let’s look at six of the most epic and arduous ultramarathons on Earth that nonetheless .

1. Barkley Marathons, Tennessee, United States

Staged in Frozen Head State Park, Tennessee, Barkley Marathons covers up to 130 miles of mountain trails, some well-kept, and others in a state of complete decrepitude. The event incorporates five loops, each around the distance of a full marathon. Runners have no access to GPS, and they are required to mark their own maps before embarking on the race. The course is unmarked except for its checkpoints. At each of these, participants tear a page from a book corresponding with their bib numbers.

Having earned the moniker “the world’s craziest race,” Barkley Marathons was created by Gary “Lazarus Lake” Cantrell, and is considered one of the most grueling ultramarathons in existence. With just 40 participants each year, made up of both men and women, the field consists of runners of all abilities. To qualify as a Barkley Finisher, contestants must complete all five loops of the course, the equivalent of five marathons. With a total elevation gain of 60,000 feet, completing all five loops is equivalent to climbing Everest twice — all within 60 hours. No one’s done it yet!

2. Iditarod Trail Invitational, Alaska, United States

Staged in Alaska on February 24 each year, the Iditarod Trail Invitational sees competitors follow the trail of the well-known sled-dog race, tackling the course either on foot or by bike. While the 130, 150, and 350-mile courses are exceptionally challenging, the 1,000-mile race is truly reserved for the elite. Competitors must contend with hurricane-force winds, with temperatures sometimes plummeting to 50 degrees below zero. To qualify for the ultramarathon, competitors must successfully complete the Invitational’s 350-mile event. They must also be able to demonstrate their winter-survival skills to event organizers.

3. Marathon des Sables, Morocco

Staged in the Moroccan Sahara, the Marathon des Sables is not for the fainthearted. It takes runners on a 6-day, 155-mile desert adventure. With a global reputation as the toughest footrace on earth, the event requires competitors to tote all of their own supplies — with the exception of their daily water rations. Like the Tour de France, every day is considered a separate stage with individual winners. At the end of each stage, competitors reach a campground with shaded tents and medical care for those who need it.

Running on sand is extremely difficult. Participants are also subjected to temperatures of over 120 degrees in addition to the high humidity and wind-whipping sandstorms that flare up from time to time. Attracting over 1,000 competitors each year, the Marathon des Sables is a feat of endurance that has grown so popular that interested parties must register almost two years ahead of time.

4. Ultra-Trail du Mont Blanc, France

It’s rare that ultrarunners have an opportunity to run through three nations during a single event. Starting in Chamonix, France, the Ultra-Trail du Mont Blanc hits the 10,000-feet elevation mark several times along the way, taking participants on a winding trail through France, Italy, and Switzerland. Obviously, competitors are treated to some awe-inspiring views; however, runners must earn those vistas. Participants will spend a great deal of their time running around those craggy mountains rather than merely gazing up at them from the foothills.

5. Badwater 135, Utah, United States

With a reputation as one of the world’s toughest ultras, the Badwater 135 runs through sizzling Death Valley. Dean Karnazes, who has completed the event a staggering 11 times, points out that it is hot enough to melt the soles of your shoes. Entrants also face the possibility of encountering any of a variety of poisonous creatures along the way, including scorpions and rattlesnakes. In 2018, when competitors embarked on the evening start, it was a sweltering 118 degrees Fahrenheit. This was nowhere close to the event’s record temperature, however. A scorching 134.1 degrees Fahrenheit was recorded at the 1913 event.

6. 6633 Arctic Ultra, Yukon Territory, Canada

Staged in Canada’s Yukon Territory, the 6633 Arctic Ultra pits competitors against some of the harshest, most extreme conditions on the planet. Entrants must contend with sub-zero temperatures and blistering cold winds. The hilly course is mostly north of the line indicating the Arctic Circle and covers exquisitely sterile terrain.

Plugged as more than a race, this adventure and expedition ends at the Arctic Ocean, subjecting entrants to some of the most extreme elements on earth. Covering a distance of either 120 or 380 miles, both races cross the imaginary border into the Arctic Circle. The 120-mile edition finishes in the town of Fort McPherson, and the 380-mile race ends in Tuktoyaktuk, on the banks of the Arctic Ocean.



David Geithner is a senior finance executive who draws upon nearly three decades of experience to serve as EVP and COO, IMG Events and On Location.

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David Geithner

David Geithner is a senior finance executive who draws upon nearly three decades of experience to serve as EVP and COO, IMG Events and On Location.