The World's Most Challenging Ultra-Marathons

Fitsok Ultra Runner
All across the world, runners are participating in the most challenging, sometimes brutal, ultra-marathons. But why?
In short, the ultramarathon is about experiencing an adventure in nature in all its forms. Ultramarathon runners seek their limits, the euphoria of surpassing them, and a sense of community with fellow ultramarathoners. Motivation can range from runner to runner. Perhaps they want to prove to themselves and the world they are capable of running such challenging distances; they want to go beyond their found limits or seek to reach that meditative tranquility that can come over you when running.
Whether you're brand new to the concept or looking for a unique challenge not found anywhere else, we'll share some of the most famous and challenging ultra-marathons today.

The Hardrock 100-Mile Endurance Run

In Silverton, Colorado, runners have 48 hours to complete 100.5 miles of extremely tough terrain. While breathtakingly beautiful, set into the San Juan Mountains, runners encounter drainages and overpasses, numerous mining ghost towns, and a mix of trails and dirt roads while doing 66,000 feet of climbing and descending. The average altitude for the course is about 11,000 feet.
Not only is the terrain extreme but so too is the weather. Summer thunderstorms can often become bad enough to force runners to huddle at tree lines or risk being struck by lightning, and there's almost always a little snow still on the course, even in mid-July. In 1995 heavy snowfall canceled the run. At the other end of the weather spectrum, abnormally dry conditions caused the run to be canceled in 2002 because of the extreme fire risk. Later, in 2019, it was canceled due to heavy snowfall again, which caused significant avalanche damage along the course.

UTMB – The Ultra Trail du Mont Blanc

For trail runners worldwide, one of the most exciting and possibly most looked-forward to ultra-marathon is the Ultra Trail du Mon Blanc in Chamonix, France. The UTMB involved roughly 106 miles of running and circumnavigating Mont Blanc, the highest mountain in Western Europe.
Approximately 2,300 people run the UTMB yearly during the last week of August or the first week of September. UTMG is recognized as one of the toughest foot races in the world, as during the 106 miles, participants travel through high elevation passes between 2,500m+/8,200ft. The mountain ranges are also subjected to changeable weather conditions, swinging from scorching summer heat to freezing high-altitude precipitation. The total elevation gain when running the UTMB covers more than 10,000m or 33,000ft of climbing and descending.
How much time do runners have to complete? Runners have forty-six hours and thirty minutes to get to the finish line, meaning they spend over two nights on the trail. Each year, the percentage of people unable to finish the race adds up to about 40% of starters.

Dragon's Back

Billed as the toughest in the world, Montane Dragon's Back race stretches right through the spine of Wales from Conwy Castle in the North to Cardiff Castle in the South. Roughly six hundred runners, called 'Dragons,' attempt the two hundred and thirty-six-mile trail (or 380km) with over six sections spanning six days.
Racers run every day until they reach a designated overnight camp checkpoint, with the course closing at 22:00 (10 pm) and restarting with staggered starts between 6 am and 9 am.
The course offers one of the most stunning views of the mountainous regions that Wales has to offer. Competition is surprisingly tight for this very off-the-beaten-path, trackless mountain race. While it sounds painful, to those who love to run the scenic views and the chance to end the race by spending the night in Cardiff Castle, it's a dream—a challenging dream—come true.


The Spartathalon is a historic, ultra-distance foot race in Greece every September. Due to its unique history and background, the Spartathalon is on the list of the world's most challenging yet exciting ultra-marathons.
Taken from the myth and legend of Pheidippides, an ancient Athenian long-distance runner who, it is said, in 490 BC before the battle of Marathon, was sent to seek help in the war from Sparta during the conflict between the Greeks and the Persians. According to an ancient Greek historian Herodotus, Pheidippides arrived in Sparta the day after he departed from Athens, then ran back to Athens to deliver the message—the journey on foot purportedly took three days.
There are many versions of this story, and inspired by it, in 1984, the International Associate "Spartathalon" was created. Runners participating in the Spartathalon have 153 miles or 246km to follow, which can be grueling. The Spartathalon course runs over rough tracks and muddy paths as it often rains during the race, crosses vineyards and olive groves, climbs steep hillsides, and, most challenging of all, a 1,200-meter ascent of Mount Parthenio in the middle of the night.
The mountain itself is covered with rocks and bushes, and despite the race being held every year, there are still no pathways over the mountain, and strong winds on the mountain path can reach temps as low as 40 degrees Fahrenheit or 4 degrees Celsius. Runners have just 36 hours to complete the race, and only a third of those who begin it get to finish it.

6633 Arctic Ultra

Another ultra-marathon billed as the toughest in the world, and for good reason, as it takes place in the Yukon Territory, Canada, during February. It's a non-stop, self-supported foot race that starts from Eagle Plains, Yukon, passes through the Arctic Circle on the Dempster Highway, continues to the banks of the Arctic Ocean, and ends in Tuktoyaktuk. Runners must negotiate 563km or 350 miles of the most remote and inhospitable landscape known to man.
Weather conditions that runners can face range from winds that blow up to 120km an hour and temperatures that can plummet to -40. In addition to possible high winds and blizzards, each participant will pull their own provisions in pulks, weighing roughly sixty to sixty-five pounds.
Of course, these few aren't all of them. There is an entire world of challenging ultra-marathons out there! But these few are some of the most famous, challenging ultra-marathons today.