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...

　　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.

　　11. The Gauntlet

　　Location: Hever Castle, Kent, England

　　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 (like it did in 2015). 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

　　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

　　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

　　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

　　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.

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　　6. Triathlon San Gil 113k

　　Location: Queretaro, Mexico

　　This 113km toughie in Querétaro (200km north of Mexico City) has been running since 1992. 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.

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　　Triathlon San Gil 113k stats

　　Swim type: altitude lake, 8

　　Swimp temp: 22°C, 5

　　Bike elevation: 774m, 3

　　Run elevation: 82m, 2

　　Run surface type: road, 5

　　Avg. high temp: 27.4°C, 10

　　Psych battle: 8

　　Isolation: 6

　　DNF rate: 3.58%, 3

　　Median time: 6:02:33, 6

　　Tough total: 56/100

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　　5. The Lost Sheep

　　Location: Kenmare, Ireland

　　During the past 14 years, the Lost Sheep Half Iron Triathlon has established itself as the toughest middle-distance race in Ireland. Organised by Cork Triathlon Club, the race is limited to 400 competitors and is a surefire bet to sell-out each season.

　　The 1.9km swim takes place in the pretty Kenmare Bay before a consistently lumpy 83km bike, which takes competitors from Kenmare out along the ring of Beara peninsula. Along the way are a duo of monster climbs, switchbacks and a 150m tunnel. While the bike course may be 7km short of official Ironman 70.3 distance, the organisers say they’ve yet to find anyone asking for more.

　　Like the bike, the 21km run course is rolling throughout and takes place on quiet country roads by the river Sheen before returning to Kenmare town over hilly terrain.

　　4. Altriman Half

　　Location: Les Angles, Pyrenees, France

　　We voted the Full Altriman triathlon the second-hardest iron race in the world last year, and the Half Version doesn’t skimp on dishing out the punishment either.

　　After a 1.9km swim at high altitude, the 92km bike heads north through the Pyrenees and includes a leg-sapping 2,100m of elevation gain and plenty of winding and hairy descents. The run is thankfully flat for the first 8km before a 6km climb takes athletes to 1,700m above sea level.

　　3. AxTri

　　Location: Aurland, Norway

　　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.

　　2. The Brutal Half

　　Location: Llanberis, Wales

　　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.

　　1. Half X

　　Location: Ambleside, Cumbria

　　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.