Are these the 7 hardest triathlons in the world?

It's time to bring out the big guns – the big ultra daddies of all triathlons – but which have we named the toughest triathlon in the world?

Deca UK

Okay, you’ve argued over our toughest iron-distance races in the world, so now it’s time to bring out the even bigger guns. Yes, the toughest triathlons in the world. Full stop.


Free from being restricted by the official 226km distances (well, we’ve thrown in our toughest iron race for good measure), these seven events aren’t for the faint-hearted. There’s a Channel Swim, a 1,800km bike course, and a run in Death Valley, with jellyfish, sharks, Jack Frost and sleep deprivation just a quartet of additional challenges that athletes can face.

How to push yourself beyond your physical limits


Make no mistake, these races are 10 out of 10 tough and some of the most relentless challenges on earth, but here we’ve judged them in comparison to each other to find the toughest triathlon in the world.

In terms of housekeeping, we’ve only included races that people can race annually or bi-annually, so there’s no Italian Triple Deca from 2013 or DIY solo challenges such as Sean Conway’s British Triathlon.

Do you agree? Start the debate in the comments below.


Ambleside, Cumbria

With a bike route on the legendary Fred Whitton cyclosportive route and a run up Scafell Pike and down again,TriathlonX is our toughest iron-distance triathlon in the world.

“The bike is based on the hilly granddaddy of all classic bike rides that happens to be 180km long. So it’s been an obvious long-held dream to have it as the showpiece of an iron-distance race,” says Anthony Gerundini, 10th 2016 and 120+ time Iron finisher. So how does this Lake District toughie fare against the ultra trio contenders?



6. Ultraman

Kona, Hawaii

Proving that the Ironman World Champs doesn’t have the hold of ultra tough Hawaiian world championship races is the Ultraman World Championships. The first Ultraman Triathlon was held back in 1983 and is a three-day, 515km multisport race.

Each race is divided into three stages over three days. Like the Ironman World Championships, the race starts in Kailua Bay, but this one throws in a 10km ocean swim to Keauhou Bay, with athletes facing open ocean swells, currents and the possibility of Portuguese Man o’ War jellyfish. This is followed by a 145km cross-country ride, with vertical climbs that total nearly 2,000m.

Stage two is a 276km ride from Volcanoes National Park to Kohala Village Inn in Hawi, with total vertical climbs of 1,219m.

Stage three is a mercifully flat 84km double marathon, which starts at Hawi and finishes on the beach at the Old Kona Airport State Recreation Area.

Each stage must be completed within 12 hours or less, with the swim portion of stage one must be completed in 5.5 hours or less. The race is limited to 40 athletes on an invitation-only basis and is the subject of Jim Gourley’s excellent book, The Race Within



5. Arch to Arc Triathlon

England and France, Europe

Okay, tri purists may take umbrage at the mixed-up run, swim and bike format, but the legendary Arch to Arc Triathlon boasts possibly the toughest swim in all of multisport, a point reinforced by the fact that only 24 people have completed the race in its 10-year history.

The race starts with an 140km run from London’s Marble Arch to Dover. Then athletes are faced with swimming across the English Channel to the French coast, navigating huge tides, one of the world’s busiest shipping routes and more for the 33.8km duration. The final discipline witnesses athletes face a 291km bike from Calais to the Arc de Triomphe in Paris.



4. Triple Brutal

Llanberis, Snowdonia

We named the single Brutal as our toughest long-distance triathlon in the world back in 2015 and it still nestles at number two. But obviously the mere 226km distance of the single seems like child’s play to some, with both double and triple options also on the weekend’s menu of leg-sapping and lung-busting specials.

The 11.4km swim takes place in the bracing waters of Llyn Padern, with athletes required to exit every two laps for some warm water down the wetsuit and a swig of tea. The 540km bike goes through the foothills of Mount Snowdon, and boasts close to 10,000m of elevation gain, with temperatures dropping to the low single figures in 2017 and athletes seeing frost form on their bike frames.

The final challenge is a 126.6km triple marathon run, including a haul all the way to the summit of Snowdon and back. This race is so extreme that you are required to bring a support crew with you to keep you safe during the night sections and on the mountain stage.

The course record is the ultra legend Anthony Gerundini – a man with over 120 iron finishes to his name – who won the race in 2015 with a 54:15hr time. After a year off in 2018, the Triple Brutal returns in 2019



3. Kona Five

Kona, Hawaii

Subjecting athletes to famous heat, humidity and howling crosswinds, the Ironman World Championships in Kona are one of the toughest iron-distance races on the planet. As the name suggests, Kona Five forces athletes to do the Kona course five times in five days and all self-supported.

The event was first completed by Keith Rieger in 70 hours and is featured in his book Kona Five Taking On Lifes Challenges and Konas Toughest Ultra-Triathlon.

And if one quintuple iron based in Hawaii isn’t enough for you, there’s also the Epic5 race, but this time across the Hawaiian Islands.



2. Deca UK

Dorney Lake, Eton, UK

Ah, Dorney Lake, that bastion of beginner short-course triathlons. Not so for Deca UK, however, with the 2012 Olympic Games rowing venue turned into a hardcore endurance ghetto for 10 days in October 2017 for the inaugural Deca UK race from Brutal Events.

The race would feature an iron-distance triathlon every day for 10 days, with athletes swimming 3.8km each morning in the chilly October lake waters of Dorney (making this extra tough, as decas are often in 50m pools).

That’s followed by 40 laps of 4.5km on the smooth and traffic-free tarmac, with the route being flat and safe but mentally taxing in its repetitive nature and solitude. The run again is another 4.5km loop allowing athletes to run on concrete or the grass verge, often under cover of darkness and in plummeting temperatures down to single figures.

What it lacks in overall elevation, it makes up for in mental torment, with the lack of views, little and poor sleep, and lap counting making this as much as a psychological challenge as a physical one. And that’s before factoring the extreme nutritional challenge of fuelling an iron a day.

Ireland’s Gerard Predergast was the inaugural Deca UK winner, completing his epic challenge at 11:06pm on the Friday night with a cumulative time of 158 hours, nine minutes and four seconds.

The UK’s toughest triathlon? Deca UK 2017 in pictures



1. Uberman

California, USA


Timmy Garrett during the 2017 Uberman swim. 21 mile smile from Catalina island to San Pedro California . . . . . . . . . . #uberman #triathlon #swimming #marathonswimming #endurance #ultrarunning #badwater #ironman #finiss #tyr #ultrasports #openwaterswimming #anotherlevel #timmygarrett #keephammering #joeroganpodcast #joerogan #nbcsports #espn #foxnews #cnn #swimbikerun

A post shared by Kamikaze chipmunk (@craiglongobardi) on Oct 10, 2017 at 9:11am PDT

With Uberman, event founder Daniel Bercu wanted to create the most uncomfortable adventure possible for endurance athletes. The first leg is a 33.7km swim in the Pacific Ocean, from Catalina Island to the shores of Palos Verdes – itself considered one of the world’s most gruelling and dangerous tests for endurance athletes, due to strong currents, ocean freighters and cruise ships, plus the chances of sharks and jellyfish.

“Most of the course is off the grid with no cell, internet or GPS,” says Bercu. “There’s no official support or aid stations. The 644km bike ride has 5,000m of climbing with technical descents. The 217km run is the Badwater course (the toughest foot race on earth) and starts at 60m below sea level in Death Valley. The loneliness and emptiness are soul crushing. The course ends at Mt Whitney trailhead, which is often snow covered.”

The 51-year-old Italian, Giorgio Alessi, became the world’s first solo Uberman finisher in 2016 with a time close to 200 hours.


* Unlike the other races, the course record here includes rest as the clock runs from when the athletes cross the start line until they cross the finish line and it’s up to the athletes when and how long they sleep for.