The World’s 10 Toughest Races

As if running a marathon wasn’t tough enough, humans decided to make it tougher—running distances of 100 or 200 or more miles!

And, if that wasn’t tough enough—humans began running ultramarathons in extreme conditions, on impossible terrain, with the threat of dangerous wildlife looming. What are these ultramarathons? We round up the top ten toughest ultramarathons in the world. 

What makes these toughest races so challenging is that they challenge both the body and mind.

Runners must train to go the distance and traverse the technical terrain—managing to not plummet to their death or run with sand chaffing their entire bodies.

They must also learn how to overcome complete exhaustion, support themselves in the world’s most inhospitable climates, and deal with situations gone wrong with no support system for days on end. 

Sit back, relax, enjoy the comfort of your home, as we introduce you to the world’s most difficult races. 

#1: Marathon des Sables

world's 10 toughest races marathon des sables
Credit: Erik Sampers

Marathon des Sables, French for Marathon of Sands (or MdS for short), is roughly a 250-kilometer journey in seven days in the hot sands of the Saharan desert. It is fully self-supported meaning there are no race crews, and you have to carry your supplies. 

You spend the night in communal goats-hair Berber tents with no sides protecting you from the desert winds. And, it is very hot. It reportedly gets to be more than 122 degrees Fahrenheit or 50 degrees Celsius.

Combining the distance, the sand, the heat, the wind, and the weight of carrying your own supplies, the MdS is undoubtedly one of the toughest footraces in the world. 

#2: UTMB

world's toughest races UTMB
Credit / license: “IMGP0217” by “mako10” is licensed under CC BY 2.0

The Ultra-Trail du Mont-Blanc or UTMB is a must for most serious trail runners. The 106 miles (171 km) race begins in Chamonix, France and follows the Tour du Mont Blanc hiking path, climbing through France to Italy to Switzerland, and back to France.

The elevation of 32,900 feet in the Alps makes it one of the steepest race courses in the world. Some of the climbs are 3,000 high.

And the weather is extreme—often going from freezing at night to blistering hot during the middle of the day. 

Some of the best runners manage to finish in just over 20 hours. It takes most hikers 9 days to complete the trail. 

The UTMB has allured most ultra-running legends and has a strict entry policy using a point system from qualifying races around the world over a two-year period and a lottery. 

#3: Badwater 135

worlds toughest races badwater

The Badwater 135 is known as one of the toughest ultras because it runs through sizzling Death Valley. It is hot enough to make your shoes melt, notes ultramarathon legend Dean Karnazes, who has raced it 11 times. Oh, and there is a good chance you’ll encounter a rattlesnake or scorpion.

Related: Who is Dean Karnazes? An In-depth Bio on the Ultramarathon Man

In 2018, the temperature at the evening start was 118 degrees F. The desert’s record high, set in 1913, is 134.1 degrees F. 

Badwater covers 135 miles, has a combined 14,600 feet of gain with a total elevation loss and gain of 20,700. The start line is at Badwater Basin, Death Valley, which marks the lowest elevation in North America at 280 feet below sea level. 

The race finishes, with a jaw-dropping ascent of 13,000 feet, to highest point in the US, the Whitney Portal at 8,300 feet. The summit painfully begins 122 miles. 

Runners have just 48 hours to complete the race. 

#4: Western States 100

western states 100

The Western States 100 is the oldest 100-mile ultra-trail race in the world. 

Beginning in 1974, the ultramarathon is well-known for its history and challenging conditions including 18,000 feet of climbing and 23,000 of descending of many trails only accessible by helicopter. 

Western States runners also experience crossing through frigid water, and temperature swings from the blistering cold with snow and ice to triple-digit heat. 

They have just 30 hours to conquer the 100.2 mile beast.

Not anyone can run the Western States. You must run a qualifier from its qualifying list during the qualifying period for the year you wish to run. The odds of getting accepted are less than 5 percent. 

Check out our other ultramarathon race profiles.

#5: Barkley Marathons

worlds toughest races barkley

The Barkleys Marathons is arguably one of the hardest ultramarathons in existence in large part because of its disorganization by design. For example, no one knows the exact distance or even the start time. Even figuring out how to apply is difficult.

The ultramarathon, which takes place in rural East Tennessee, involves running 5 loops of anywhere between 20 or 26 miles of uncleared trials that cut through briar patches leaving runners battered and cut up. 

The total elevation gain of 60,000 feet (if you complete all five loops) is the equivalent of climbing Mount Everest two times from sea level. The total elevation gain and loss combined is close to 120,000 feet (so climbing and descending Mount Everest twice…from sea level). 

It regularly ends with no finishers. Since 1986, there have only been 15 Barkley finishers.

Related: Who is Lazarus Lake? The Man Behind the Barkley Marathons

#6: The 4 Deserts Ultramarathon Series

4 deserts worlds toughest races

The 4 Deserts is an ultramarathon series of four 6-stage 250k (155 mile) multiday races taking place in four deserts around the world. 

Runners must traverse the “driest, hottest, coldest and windiest places on earth, testing their limits both physically and mentally.”

And they do this self-supported. Only a tent and water are provided for 4 Deserts.

The highest elevation runners run is in China with a total elevation gain of 14,635 feet of elevation gain and total elevation loss of 13,293 feet. Runners will experience extreme temperatures from 40 degrees Celsius (104 degrees Fahrenheit) in the hottest deserts to 20 Celsius (-4 degrees Fahrenheit) in Antarctica, and everything in between.

#7: The Moab 240

The Moab 240 Endurance Run is a footrace through some of Utah’s most stunning and challenging terrain. The terrain (and distance) is what makes the Moab 240 so difficult. 

It runs 240 miles through deserts, two mountain ranges, slick rock, and canyons.

There are also large boulders, cliff edges and loose rock, coupled with steep inclines. The course itself is a full circumnavigation of the Moab desert in Utah, which sees runners tackle and conquer two mountains ranges: Shay mountain and the La Sal Mountain ranges.


It has an ascent of 29,467 feet and a cutoff time of 112 hours. 

Each participant must have fulfilled an eight-hour trail work requirement to qualify.

#8: HURT 100

The Hawaiian Ultra Running Team’s Trail 100-Mile Endurance Run (HURT100) is a challenging and very technical ultramarathon taking place through pig trails, rain forests, and single-track paths located in the hills above Honolulu. 

The 100-mile race is known for its grueling terrain including loose soil, roots, puddles, and mud. The narrow trails traverse along exposed ridges and past vertical embankments.

Coupled with the danger are stunningly beautiful views of the O‘ahu coastline as well as the Pacific Ocean. 

Participants for the event are chosen via a lottery selection process. Entry is limited to only 125 participants.

#9: Hardrock 100

The Hardrock Hundred Mile Endurance Run takes place in southern Colorado’s grueling yet beautiful Rocky Mountains. The course ascends nearly 34,000 feet over 100.5 miles at an average elevation of 11,000 feet, topping out at the 14,048-foot Handies Peak. 

Hardrock is designed to traverse some of the steepest and hardest routes in the Rockies, touring many defunct mining operations. Indeed, the race is dedicated to the memory of the “hard as rock” miners who settled in the area and built the mining trails on which much of the race is run. The race is typically run when during peak wildflower season.

Most competitors will see the sun rise twice; the winner will finish in about 24 hours. Entry is difficult requiring qualification and a lottery selection. 

#10: The Jungle Marathon

While the other ultramarathons offer extremely dangerous terrain and weather, the Jungle Marathon offers the threat of life-threatening wildlife. Indeed, some dub it the most “terrifying adventure in the world.”

The 200+ km race includes swamps, snakes, mosquitos, leeches, crocodiles, jaguars, howler monkey, spiders, scorpions, wasps, and other typically unwanted wildlife. 

Runners have six days to battle through the inhospitable jungle terrain, on paths only penetrable by boat, that chokes its visitors with heat and humidity. It is a self-sufficient race so no supplies are provided. 

Runners are often awoken by bites from ants or other creatures.

But the Jungle Marathon is also beautiful. Taking place in Manu National Park and ending at an UNESCO World Heritage Site, runners experience the breathtaking cloud forest running from the Andes mountains to the Madre de Dios River. They stand above the clouds (in air so thin it is difficult to breathe), peering down a massive valley into a sea of green trees. 

If you’re interested in conquering the ultramarathon distance, check out our ultramarathon training plans.

Whitney Heins
Whitney Heins is the founder of The Mother Runners and a VDOT-O2 certified running coach. She lives in Knoxville, TN with her two crazy, beautiful kids, pups, and husband. She is currently training to qualify for the 2024 US Olympic Trials marathon.

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