Ultra running is one of the most demanding sports on the planet and poses the challenge of completing a race further than the usual marathon distance of 26 miles.
Some of the world’s fittest and most daring runners are willing to push the envelope of what is physically possible as they take on outrageous routes featuring dizzying ascents, rugged terrain and punishing conditions.
At the most elite end of the ultra running spectrum are races that push the very best to the absolute limit – from the legendary and eccentric Barkley Marathons in the USA to the formidable Spine Race in the UK, we take you through the most challenging events across the globe.
1. The Barkley Marathons (USA)
The Barkley Marathons is as daunting as it is mysterious. It is near-impossible to enter – and complete – with only 15 people having finished since 1986 and none since John Kelly in 2017.
Organised by the whacky character that is Gary “Lazarus Lake” Cantrell, the race consists of five laps of just over 20 miles, with competitors given 12 hours to finish each lap of the race.
Taking in countless metres of elevation gain, in what quite often turns into extreme weather conditions, the Barkley takes no prisoners.
2. The Tunnel (UK)
Forget the stunning mountain ranges and open skies associated with your typical ultramarathon – The Tunnel is a terrifying, 200-mile race that takes place almost exclusively underground.
Held in the Combe Down tunnel in Bath, competitors have 55 hours to complete 100 ‘out and back’ loops of the tunnel, with a brutal cut-off time of 27 hours 30 minutes at the 100-mile mark.
In an insane physical and mental test, competitors run in complete darkness between 11am and 5am, with the rest of the time spent running under a small amount of artificial light. It is described as the equivalent of running an ultramarathon in a sensory deprivation tank.
3. Spartathlon (Greece)
Shrouded in ancient Greek history, the Spartathlon recreates the arduous journey of an ancient Athenian and is an eye-watering examination of runners’ durability.
Held in Greece every September, the 154-mile race follows the footsteps of Pheidippides, who in 490BC was sent to Sparta to seek help in the war between the Greeks and the Persians before the battle of Marathon.
In 1982, a former British RAF officer John Foden pondered whether a modern man could complete the distance and set out on the run with four others, with the fastest of the group, John Scholten, finishing the challenge in just under 36 hours.
Thus, today’s event has a 36-hour time limit and includes a 1,000m mountain which must be traversed in the middle of the night, during freezing temperatures. It has only been completed by some 700 runners.
4. Moab 240 (USA)
Athletes flock deep into the Utah desert every October to take on the Moab 240, another course capable of devastating even the most established ultra runner. A single loop, encompassing much of the spectacular Canyonlands and Arches national parks, the race covers 240 miles and almost 9,500 metres of elevation gain.
With a 118-hour cut-off time and climbs to peaks above 3,000 metres in elevation, this punishing test of endurance will not only destroy a competitor’s legs, but also their resolve too, as they constantly ascend and descend the rolling terrain.
5. Badwater 135 (USA)
Known for many years as the ‘toughest foot race on earth’, the sweltering Badwater 135 starts below sea level in California’s Death Valley and keeps on climbing for a draining 135 miles.
Running in temperatures that can reach upwards of 50 degrees celsius, an international field of athletes compete every year for the elusive race win and the infamous Badwater Belt Buckle, which is awarded those tough enough to finish in under 48 hours.
David Goggins is among those who have taken it on and conquered it, finishing fifth behind Scott Jurek in 2006.
6. Self Transcendence 3,100 (USA)
When it comes to distance, nothing tops the Self-Transcendence 3,100, which is renowned as the the longest known foot race on earth.
After its first year of running, the original race distance of 2,700 miles was deemed too meagre and increased to a whopping 3,100 miles by founder Sri Chinmoy.
And the ultimate test of endurance offers little in the way of natural landscapes – it is made up of a mind-numbing 5,649 laps of a small city block in Queens, New York.
Runners must average a grueling 59.62 miles per day, with only 52 people ever able to complete the feat.
7. Spine Race (UK)
While the summer edition is taxing enough, the winter Spine Race event is on another level of suffering as competitors run the length of the Pennine Way, covering 268 miles and climbing a staggering 13,300m.
Tackling knee-deep bogs, endless moors and at times horrendous weather conditions, participants have a week to complete the challenge, which hikers usually put aside up to three weeks to finish.
In 2023, the winner of the Winter Spine race, Damian Hall, took just over three and a half days to complete the challenge, in a new men’s course record of 84 hours and 36 minutes. The overall course record is held by Jasmin Paris (83:12:13).
8. Marathon des Sables (Morocco)
The scorching Sahara Desert plays host to the unique six-day Marathon des Sables, which sees participants cover 251km in searing southern Morocco heat.
Runners are all alone in the desert as they’re required to be self-sufficient, carrying all they need on their backs, as they tackle sand dunes, rocky jebels and white hot salt plains.
What sets the race aside from the comparably simple task of a typical ultramarathon is its emptiness – competitors traverse through largely uninhabited, inhospitable desert, often with nothing but their own thoughts for company.
9. Leadville Trail 100 Run (USA)
Made famous by the bestselling book ‘Born to Run’, the Leadville Trail 100 Run has widely been regarded as one of the most physically challenging 100-mile races on earth, with the event itself starting at over 3,100m of elevation in Leadville, Colorado.
The air is so thin that even walking up the steps to the race start is a challenge, let alone running 100 miles. Competitors are posed the near-impossible task of climbing over 4,500m during the course of the race, including ascending the 4,300m Pikes Peak.
Race founder Ken Chlouber tells those brave enought to enter to “make friends with pain and you’ll never be alone” as they make their way through some of the toughest terrain in Colorado.
The famous Leadville Belt Buckle is on offer to those unimaginably fit enough to finish in under 25 hours.
10. HURT 100 (USA)
The clue is in the name for the HURT 100 as runners battle through the humidity of the rainforest above Honolulu on the Hawaiian island of Oahu.
Extremely desirable among the most insane ultra runners in the world, the 100-mile event in the heart of the Pacific Ocean is limited to only 135 entrants.
Tropical conditions and tough underfoot terrain make for a challenge that takes in some of the most stunning trails on the planet.