11 of the toughest middle-distance triathlons on the planet

For many, taking on a middle-distance triathlon is hard enough, but what if you want to make it extra challenging? Well, then you’d probably want to take on one of the toughest 70.3 races in the world…

• 70.3 run advice and sessions from Will Clarke
• 70.3 swim advice and sessions from Lucy Charles
• 70.3 bike tips and sessions from David McNamee
• 11 middle-distance training tips for beginners

To help you on your masochistic pursuit of a challenge, we’ve pulled together a list of middle-distance races that’ll really test you.

Best middle-distance triathlon races

11. The Gauntlet

Location: Hever Castle, Kent, England

Next race: 27-28 September 2025

The Hever Castle leg of the Castle Race Series is famous for hosting the world’s largest children’s triathlon and more beginner-friendly races than you can poke a track pump at. But what’s often overlooked is how deceptively tough the bike and run routes are of the longer races.

After a unique 1.9km swim that features a Japanese teahouse and two bodies of water (a lake and a river Eden tributary), the Gauntlet‘s 90km two-loop bike takes in the high weald of Kent and Ashdown forest. It’s relentlessly rolling and scenic (if you can muster the energy to sightsee), with the high/low point being the 7km-long climb on the High Road south of Hartfield.

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The two-loop run, meanwhile, is set on leg-sapping trails and bridle paths to Chiddingstone and back, and is one that’ll keep you on guard throughout and can be very sticky if it’s rained before the race. There’s also a nasty little climb at the end of each loop before one of the UK’s best finishing chutes (and post-race food).

10. Challenge Walchsee-Kaiserwinkl

Location: Walchsee, Austria

Next race: 26 June 2025

Set in the majestic Austrian Tyrol region, Challenge Half Walchsee-Kaiserwinkl gives Challenge Wanaka a push as the race organiser’s most beautiful event. But, like that New Zealand stunner, there’s a sting in the tail provided by the testing bike leg.

• The world’s most scenic bike legs

After a swim in the crystal-clear Walchsee lake, the two-loop 90km bike takes in the mountainous panorama of the Kaiserwinkl region, subjecting athletes to over 1,000m of elevation gain along the way. The 21km run course is mercifully flat and heads around the lake, along the promenade and through alpine meadows.

9. Israman 113

Location: Eilat, Israel

Next race: 31 January 2025 (subject to ongoing political unrest in the region)

Israman began life in 1999 and remains the only long-distance triathlon in the Israel’s dedicated multisport scene. Hosting both 113km middle and 226km long-course races, the Israman starts in the southern holiday resort of Eilat, nestled between the mountainous terrain of Jordan to the east and Egypt to the west.

The race then heads north after a swim in the salty Red Sea for the unforgiving Negev desert, starting with a 12km climb straight out of transition up to 600m above sea level. The temperatures in the desert can vary from freezing to 30C, with 60mph crosswinds adding to the gruelling mix.

If the run elevation gain looks small, that number is deceptive (so we’d added a few marks), with the course unique in middle-distance triathlon in that it’s sharply downhill for the first 12km before a coastline finish.

8. The Snowman Legend

Location: Plas y Brenin, Snowdonia, Wales

Next race: 3 August 2025

If snow is unlikely in July, even in the seeming microclimate that is Snowdonia, the Snowman delivers on its promise of being top race organiser Always Aim High’s toughest middle-distance race.

The swim kicks off in the shallow Llyn Mymbyr before an epic 90km bike through the heart of the Snowdonia National Park. The run nearly features as much elevation gain as the bike, taking athletes to the summit of Moel Siabod and straight back down to the finish line at Plas y Brenin.

7. Ironman 70.3 St. George

Location: St George, Utah, USA

Next race: 10 May 2025

It’s the race where Alistair Brownlee made his statement of 70.3 intent in May 2017 but, despite his course record of 3:41:58, Ironman 70.3 St George is actually one of the toughest Ironman 70.3s on the circuit for us mere mortals.

The one loop swim takes place in the calm, if chilly, waters of the Sand Hollow Reservoir before the bike leg takes in rolling hills and the signature climb up – and through – Snow Canyon State Park. The run, meanwhile, includes scaling Red Hills Parkway and going through the Red Cliffs Desert Reserve, all under the scorching Utah sun.

Location: Queretaro, Mexico

Next race: 25 & 26 July 2025

The original 113km toughie in Querétaro (200km north of Mexico City) started in 1992 but discontinued in 2022 after taking a break in 2020 and 2021 due to the Coronavirus pandemic.

There’s now an 86km middle-distance triathlon new for 2025 that still offers a decent challenge and an opportunity to test your fitness.

Altitude more than elevation gain plays a major role in the athlete’s toils, with the swim taking place in an artificial lake at an altitude of 2,000m.

The bike then climbs even higher on the bike course into the Querétaro Mountains. The run is thankfully flat but the mid-summer Mexican sun keeps the torment coming.

Triathlon San Gil 86k stats

Swim type: altitude lake, 8
Swim temp: 22°C, 5
Bike elevation: 787m, 2.
Run elevation: 62m, 2
Run surface type: road, 5
Avg. high temp: 27.4°C, 10

5. The Lost Sheep

3.  AxTri

Location: Aurland, Norway

Next race: TBC

If a race start on Laguna Beach conjures images of Thailand, the AxTri’s setting couldn’t be further from it. The Aurland fjord is one of the deepest in the world and water temperatures range from 8-20C depending on the depth.

The long 98km bike route boasts 3,100m of elevation gain and travels from Aurland, over Aurlandsfjellet (1,320m above sea level), down to the village of Erdal by the fjord, back the same way over the mountain to Aurland and the eastern end of the lake Vassbygdi-vatnet (T2). The air temperature may drop below the freezing point on top of the mountain on the bike leg, even in August.

Athletes have a 2km respite from the hills at the start of the run before things get hilly for the final 19km, with over a thousand metres of climbing. Support crews are allowed to follow athletes up the valley, but each athlete must carry their own backpack containing all their gear. The run up Aurlandsdalen has seen temperatures close to 30C, so athletes have to prepare for all weather conditions, as well as aching calfs, quads and lungs.

AxTri stats

Swim type: fjord,10
Swimp temp: 8-20°C, 10
Bike elevation: 3,100m, 10
Run elevation: 1,100m, 10
Run surface type: trail, 7
Avg. high temp: 14°C,8
Psych battle: 10
Isolation: 10
DNF rate: 3.44%, 3
Median time: 9:02:24, 9

Tough total: 87/100

2. The Brutal Half

Location: Llanberis, Wales

Next race: TBC

Set in the picturesque and dramatic scenery of Llanberis in Snowdonia, Northern Wales, the Half Brutal is the shortest brother of the increasingly (in)famous Brutal family, which also include the full length (up there as the toughest Iron event on the planet, the double and triple.

The swim section takes place in the chilly Lyn Padarn lake’s water (two laps). What follows is worth the race name: a two-lap bike with 1,524m of total vertical gain in total, one 8km lap of running around the lake to stretch the legs, and then a leg-sapping, lung-busting climb to the top of Mount Snowdon, the highest mountain in Wales, and back down again.

Brutal Half stats

Swim type: lake, 7
Swimp temp: 15°C, 8
Bike elevation: 1,513m, 7
Run elevation: 920m, 9
Run surface type: mountain paths, 9
Avg. high temp: 14°C, 8
Psych battle: 10
Isolation: 10
DNF rate: 12%, 10
Median time: 10:40:53, 10

Tough total: 88/100

1. Half X

Location: Ambleside, Cumbria

Next race: TBC

The Half X is the shorter sibling of the infamous TriathlonX in the Lake District, a race we named as the toughest long-distance triathlon in the world. And like it’s bigger brother, the bike route takes place on the legendary Fred Whitton cyclosportive route and features a run up Scafell Pike and down again.

With 2,800m of elevation gain, the bike route takes in six hill climbs over 20%, with Hardknott Pass topping out at 33%. The half marathon run, meanwhile, is imposing in its own right, taking in the peaks of Nab Scar, Heron Pike and Great Rigg before the final ascent of Fairfield Summit.

Half X stats

Swim type: lake swim, 7
Swimp temp: 18° 7
Bike elevation: 2,800m, 10
Run elevation: 1,079m, 10
Run surface type: Rocky trails, 10
Avg. high temp: 17°C, 6
Psych battle: 10
Isolation: 10
DNF rate: 17.3%, 10
Median time: 9:01:17, 9

Tough total: 89/100