Ultramarathons easily earn the spotlight for their grueling conditions and lengthy distances, but a few of the 26.2 races are beefing up the traditional event with tougher courses, meaning more variety for the endurance runner.
In many of these extreme races, qualifying is difficult and finishing percentages can be drastically lower than a conventional road race. Still, it's a test many have chosen to take. There are dozens of extreme races to choose from—here's a look at 10 of the toughest footraces in the world.
Pikes Peak MarathonAugust 16, 2015 - Colorado Springs, Colorado 1 of 11
The Pikes Peak Marathon starts on the streets of Manitou Springs and then climbs to the top of a 14,000-foot summit. According to race officials, once runners get above the tree line, it takes about 30 minutes to cover a single mile.
The second half of the marathon boasts a descent of treacherous rocks and roots. In the second half of the race, the temperature plummets some 60 degree to about 30 degrees Fahrenheit.
The Pike Peak Marathon accepts only 800 runners and costs $130 per person plus fees.
Comrades MarathonMay 31, 2015 - Durban, South Africa 2 of 11
The Comrades Marathon is 55.3 miles (89 kilometers) and travels from Durban City Hall along South Africa's coast up to Pietermaritzburg. Each year, the course direction switches from Durban to Pietermaritzburg (the up run) and Pietermaritzburg to Durban (the down run).
In this race, runners must make cut-off times at checkpoints or else they're disqualified. Runners have only 12 hours to complete the 89-kilometer course.
The Comrades Marathon is limited to 23,000 runners and costs about $175 per person.
Grand to Grand UltraSept. 20-Sept. 26, 2015 - Grand Canyon, Arizona 3 of 11
Photo Courtesy of Grand to Grand Ultra
The Grand to Grand Ultra is a 170-mile ultramarathon staged over a week. From the starting line at the Grand Canyon, runners take off on a course that passes by cliffs, canyons, valleys and across sand dunes. This run is self-supported, which means all participants carry their own food and water. The course ends on the summit of the Pink Cliffs of the Grand Staircase.
Grand to Grand Ultra is limited to 250 runners and costs about $3,200 per person.
6633 UltraMarch 20, 2015 - Yukon 4 of 11
This 350-mile self-supported ultramarathon starts at the Eagle Plains, Yukon. Participants are expected to carry or pull their gear on sleds as they make their way across the Arctic Circle to the Arctic Ocean at Tuktoyaktuk. Participants battle sub-zero temperatures and blistering winds as they try to complete the course in the allotted eight days.
According to race organizers, in the seven years of the ultra, only 11 have finished the 350-mile course. The 6633 Ultra costs about $3,177.
Charlie Ramsay RoundDate determined by participant - Scotland 5 of 11
The Ramsay Round is a 60-mile challenge up 24 summits in 24 hours. The course starts and ends at the Glen Nevis Youth Hostel and includes a climb up the Ben Nevis, the highest peak on the British Isles.
The Round requires navigation over remote terrain and sometimes battling unseasonably bad weather. Competitors are advised to try the mountain challenge in May, June or July when daylight hours are longest.
Leadville Trail 100Aug. 22, 2015 - Leadville, Colorado 6 of 11
Photo Courtesy of Glen Delman Photography
The Leadville Trail 100, dubbed the "Race Across the Sky," is a 100-mile out-and-back run along the Colorado Rockies. Runners face elevations from 9,200 feet to 12,600 feet as they try to complete the mileage in less than 30 hours. Most of the trail is on forest floor with some mountain roads.
The Leadville Trail 100 is limited to 800 runners and costs $315 per person plus a $15 lottery fee, which is donated to the Leadville Legacy Foundation.
Inca Trail MarathonJune 5-13, 2015 and Aug. 1-13, 2015 - Peru 7 of 11
Photo Courtesy of Andes Adventures
No bib numbers at the Inca Trail Marathon, which takes place in Machu Picchu National Park. The single-day marathon is part of a trip spread out over several days. Because of the treacherous terrain, the trail has been compared to a 50-mile trail run. Altitudes range from 8,000 feet to 13,779 feet along three mountain passes. Organizers boast that the trail is even tougher than the Pikes Peak Marathon.
The Inca Trail Marathon is limited to about 45 runners and costs about $2,995 per person.
4 Deserts SeriesMarch 8-14 (Sahara); May 31-June 6 (Gobi); October 4-10 (Atacama); November 2016 (Last Desert) 8 of 11
Photo Courtesty of 4Deserts.com
The 4 Deserts Series takes runners to four places on the planet, including the Atacama Crossing in Chile, the Gobi March in China, the Sahara Race in Jordan and the Last Desert in Antarctica. Each race covers about 150 miles over seven days. Runners face sand dunes, river crossings, dirt tracks and more.
All races require participants to carry all their equipment, food and shelter along the journey. As of 2014, there were 126 people who have completed all four races.
4 Deserts costs about $2,100 per person per race.
Hardrock 100July 10, 2015 - Silverton, Colorado 9 of 11
At the Hardrock 100, participants run 100 miles along Southern Colorado's San Juan Range. Runners face dirt roads, trails and cross-country landscape as they battle up and down a vertical gain of 33,992 feet. The highest elevation reaches 14,048 feet.
Runners have 48 hours to finish the course, where they are expected to "kiss the Hardrock"—a ram's head painted on a large stone—to finish.
The Hardrock 100 is limited to about 150 runners and costs $295/ person.
Badwater UltramarathonJuly 28-30, 2015 - Furnace Creek, California 10 of 11
Photo Courtesy of Evanescent Light Photography
Only 100 men and women are given the chance to run the Badwater Ultramarathon, a grueling 135-mile race from Death Valley to Mount Whitney, California, the highest point in the United States. The course includes three mountain ranges, with July temperatures that easily top 100 degrees in the shade. Runners have 48 hours to finish the race.
The Badwater Ultramarathon is limited to about 100 runners and costs $1,195 per person.