Ultramarathon

 ( Endurance Games ) 

The format of ultramarathons and the courses vary, ranging from single loops (some as short as a track),If the loop is less than , run direction changes every 2–4 (sometimes 6) hours [Citation Needed~~~~Mark Halsey] to point-to-point road or trail races, to cross-country rogaining. Many ultramarathons have significant obstacles, such as inclement weather, elevation change, or rugged terrain. Usually, there are , whether every lap of a track, small road or trail loop courses, or extending up to perhaps , where runners can replenish food and drink or take a short break.

There are some self-supported ultramarathon stage races in which each competitor has to carry all their supplies including food to survive the length of the race, typically a week long. The Marathon des Sables 6-day stage race in Morocco and the Grand to Grand Ultra in the U.S. are examples.

The International Association of Ultrarunners (IAU) organises the World Championships for various ultramarathon distances, including , , 24 hours, and ultra trail running, which are also recognized by World Athletics. Many countries around the world have their own ultrarunning organizations, often the national athletics federation of the country, or are sanctioned by such national athletics organizations.

50-kilometer and 100-kilometer races are recognized as World Records by World Athletics, the world governing body of track and field. The International Association of Ultrarunners recognizes IAU World Records for 50-kilometers, 100-kilometers, 6 hours, 12 hours, 100 miles, 24 hours, 48 hours, and 6 days.

There are ultramarathon racewalking events that are usually 50 km, although 100 km and 100-mile (160 km) "Centurion" races are also organized. Furthermore, the non-competitive International Marching League event Nijmegen Four Days March has a regulation distance of 4 × 50 km over four days for those aged 19 to 49.

In 2021, concerns were raised about planning and medical care available for ultramarathons in China, after 21 racers died from hypothermia while competing in an ultramarathon in the Yellow River Stone Forest. The government later announced a ban on "extreme" competitions.

In August 2023, a partnership between Ultra-Trail du Mont-Blanc (UTMB) and Ironman Triathlon was announced and the new formation of the UTMB World Series, an ultra-distance circuit that culminates with UTMB held in August. Concerns have been raised about rising entry fees, homogenization of racing experiences, and bulldozing of smaller events.

Starting in January 2022, the IAU began to recognize and ratify performances as IAU World Records. World Athletics also began to ratify the 50k distance as a World Record for both mixed and women, respectively, along with 100k. The events considered IAU World Records are: 6, 12, 24, and 48 hours along with 50 and 100 miles. Records in the 6 day event are called World Best Performances by the IAU.

Performances exceeding the current IAU records but which have not yet been ratified include the following:

• Stine Rex ran 435.564 km at the 2024 GOMU 48 hour world championships. The GOMU lists it as a "All Time World Best" performance.
• Stine Rex ran 913.6 km at a 6-day race in Denmark during August and September 2024.
• Ivan Zaborsky ran 1047.554 km in six days in Vallon Pont d'Arc, France, finishing on 4 May 2025. iRunFar: Megan Eckert and Ivan Zaborsky Set Women’s and Men’s 6-Day Running World Records
• Megan Eckert ran 970.685 km in six days at the same race in Vallon Pont d'Arc. iRunFar: Megan Eckert and Ivan Zaborsky Set Women’s and Men’s 6-Day Running World Records
• Matthieu Bonne ran 485.099 km in 48 hours in Pabianice, Poland, finishing on 1 June 2025. iRunFar: Matthieu Bonne and Patrycja Bereznowska Set New Men’s and Women’s 48-Hour World Records.
• Patrycja Bereznowska ran 436.371 km in 48 hours at the same race in Pabianice. iRunFar: Matthieu Bonne and Patrycja Bereznowska Set New Men’s and Women’s 48-Hour World Records.

The IAU World Records and World Best Performances as of April 2025 are as follows.

Until 2021, the IAU also kept records for 1000 km and 1000 miles. The final records were: IAU: Final WBP and WABP Records: 1000K, 1000M

• South Africa hosts a number of notable ultra marathon events.
• On road: the world's oldest and largest ultramarathon, the Comrades Marathon. Approximately 12,000 runners complete the Comrades each year, out of approximately 17,000 who start, with 23,961 competing in 2000.
• The Two Oceans Marathon in Cape Town in the southern autumn attracts approximately 11,000 runners.
• The Grand Raid de la Réunion is held annually on Réunion in October, crossing the island over with an altitude gain of . This race attracts 2,350 competitors, with 1,000 runners from overseas.
• The Marathon des Sables is a 6-day stage race which covers through the Sahara desert in Morocco.
• The Spanish Canary Islands off the African coast are the location of some prestigious ultramarathons, including the 46-mile Transvulcania.

• In Israel, two major ultramarathon races are Mount to Valley relay race, over 215 km, from the hills of the Upper Galilee to the Jezreel Valley; and the Valley Circle race in the Jezreel valley, containing several distances, including 160 km and 200 km.
• India's first ultra-marathon, the Bangalore Ultra, was held in 2007. Since 2010, the Indian Himalayas have hosted La Ultra – The High, a 333 km course crossing Khardung La, touted to be the world's highest motorable mountain pass.
• Japan had its first 100 km event in 1987 as Lake Saroma Ultramarathon and hosted the IAU 100 km World Championship in 1994 (Lake Saroma), 1998 (River Shimanto) and 2005 (Lake Saroma). Japan hosts more than 50 ultramarathon events throughout the year, including the Trans Japan Alps Race (TJAR) ( with more than cumulative altitude gain crossing Japan Alps, crossing Japan's mainland from Japan Sea to Pacific Ocean in 7 days),NHK team, 激走! 日本アルプス大縦断 密着、トランスジャパンアルプスレース富山~静岡415km, 26 April 2013, Hasetsune cup ( in steep foggy mountains)RUNTRAIL editors, RUN+TRAIL vol.2 トレイルランレースをはじめよう ハセツネ/UTMF完走法 (SAN-EI MOOK),22 Aug 2012, and the Ultra-Trail Mt. Fuji ( loop around World Heritage Mount Fuji with a cumulative altitude gain of about ).
• The Gobi March in northwest China was China's first ultramarathon, first staged in 2003. The Gobi March is part of the 4 Deserts Race Series.
• Hong Kong Four Trails Ultra Challenge is a 298 km-long uninterrupted race, the first ultramarathon-class race in Hong Kong.

In Australia, the Westfield Ultra Marathon was an annual race between Sydney and Melbourne contested between 1983 and 1991. Greek runner Yiannis Kouros won the event five times during that period. Australia is also the home of one of the oldest six-day races in the world, the Cliff Young Australian 6-day race, held in Colac, Victoria. The race is held on a 400-meter circuit at the Memorial Square in the centre of Colac and has seen many close races since its inception in 1984. The 20th Cliff Young Australian six-day race was held between 20 and 26 November 2005. During that event, Kouros beat his existing world record six-day track mark and set a new mark of . The Coast to Kosciuszko inaugurated in 2004, is a marathon from the coast to the top of Mount Kosciuszko, Australia's highest mountain.

Australia has seen a steep growth in ultrarunning events and participants in recent years. Many new races have come into inception, covering a range of ultramarathon distances from 50 km right through to multi-day events. The cornerstone of Australian Ultra events is such races as Ultra-Trail Australia 100, The Great North Walk Ultras, Surf Coast Century, Bogong to Hotham, Alpine Challenge, GC50 Run Festival, and the Cradle Mountain Run. The Australian Ultra Runners Association (AURA) has a comprehensive list and links of events and their respective results.

In New Zealand, the Kepler Challenge is held on a trail through Fiordland National Park. It has been running since 1988 and is one of the country's most popular races. The Tarawera Ultramarathon is currently one of the most competitive ultras in New Zealand and part of the Ultra-Trail World Tour.

The UTMB, through France, Italy, and Switzerland has been considered the world's most competitive trail ultra. The other races in the UTMB festival, including the CCC, TDS, and OCC, are also significant events in the ultrarunning calendar.

There are several 100-mile ultramarathons held annually in North America. The Western States Endurance Run is the oldest 100-mile trail run in North America. The race began in 1977, founded by Wendell Robie, of Auburn California.

The first mountain trail ultramarathon held in the United States was the 1911 Mount Baker Race (50K), in Bellingham, Washington. Runners raced by car or train to the trailheads, ran up to the summit of Mount Baker, and then back down to the city.

An early ultramarathon was held in Mexico in 1926, and at the time was part of the Central American Games. Tomas Zafiro and Leoncio San Miguel, both Tarahumara Indians, ran 100 km from Pachuca to Mexico City in 9 hours and 37 minutes. At the time, the Mexican government petitioned to include a 100 km race in the 1928 Summer Olympics in Amsterdam.

In 1928, sports agent C. C. Pyle organized the first of two editions of the 3,455-mile-long Bunion Derby. The first went along U.S. Route 66 from Los Angeles to Chicago before heading toward New York; the 1929 Derby reversed the route. Neither the race nor the accompanying vaudeville show was a financial success.

In the 1980s, Gary "Lazarus Lake" Cantrell and Karl "Raw Dog" Henn conceived the Barkley Marathons, an annual trail race held in March or April in Frozen Head State Park, Tennessee. The course is approximately 20 miles long with approximately 11,000 feet of vertical climb, and runners have 60 hours to complete five laps. The run is notorious not only for its difficulty but also for its secretive nature; entrants must undergo a selection process and entry dates and requirements are not announced, meaning entrants rely on word-of-mouth for details on how to enter. The first Barkley Marathons took place in 1986, and as of 2025, the full, five-loop race has been completed a total of 26 times by 20 runners.

Since 1997, runners have been competing in the Self-Transcendence 3100 Mile Race, which is billed as the longest official footrace in the world. They run 100 laps a day for up to 50 days around a single block in Queens, NY, for a total distance of . The current record holder is Ashprihanal Pekka Aalto, at 40 days 09:06:21 for a daily average of in 2015.

Several 10-day races are also regularly available in the US at venues that hold 6-day races: Across the Years (in Arizona), Sri Chinmoy (in New York) and 6 Days in the Dome (Wisconsin).