How do you like to spend your weekend off?

That doesn’t quite cut it for some people, who choose to run a 200-mile ultra-marathon in a disused railway tunnel instead.

The Tunnel Ultra is a race like no other. It’s easy to find longer events. Some even involve repeating the same loop for days on end. But nowhere else can you take part in a race so twisted that you spend more than two days in darkness doing a one-mile shuttle run 200 times, or so punishing that one runner went temporarily blind – then thanked the race organiser for the privilege.

No outside support is permitted, headphones are banned and runners are not allowed to run side by side. Oh, and there is a strict time limit of 55 hours.

The Tunnel website describes it as “a mind-bending test of extreme endurance and sensory deprivation”. It is more health warning than marketing slogan.

“I could be sat on the sofa watching Strictly with the wife and kids. Or do I want to be in a dripping tunnel, tired and miserable, knowing I’ve got work on Monday?” Guy Bettinson, a 45-year-old programme manager from Cumbria who won the Tunnel in 2020, wonders out loud. “I’d rather waste my weekend putting myself through misery.”

“It’s so pointless. You’re not getting from A to B, which makes it such a massive mental challenge,” says Andy Persson, another finisher that year. “If you can push your mind further than you think is possible, it’s quite empowering.”

Christian Mauduit, a French software engineer who won the 2021 edition, says: “I’m chasing that internal adventure – that meeting with myself. It’s like a little kid – they want to see how close they can come to the fire. I’m still that little kid.”

Bettinson describes every ultra-marathon start line as a “mid-life crisis anonymous meeting”. “We’ve all got issues,” he says. “It’s clearly some kind of therapy.”

The race takes place in Combe Down Tunnel, a mile south of Bath city centre, and starts at 4pm on a Friday in March. No more than 40 runners make it that far, partly because of a strict – and deliberately opaque – qualification process and largely because the tunnel is not big enough to accommodate many more. “Even the start line is weird,” says Mauduit. “You have to stand one behind another in a queue.”

Combe Down was restored as a cycle path in 2013 after 47 years under weeds. It is the UK’s longest foot tunnel – and the obvious setting for an ultra-marathon if your name is Mark Cockbain.

“I like things that have got an X-factor,” says Cockbain, a prolific former ultra-runner who set up the Tunnel in 2019 to add to his brilliant yet brutal portfolio of events as a race organiser. “As soon as I got permission to use the tunnel, it was a no-brainer.”

The race is low key in the extreme. A fold-up table outside one end of the tunnel serves as race HQ. There is no shelter or rest area to speak of unless runners have the foresight to bring a camping chair. They must all share a portable toilet which, by the end of the weekend, would not look out of place at a music festival. Refreshments are limited to water and tea, while the most luxurious snacks are Pot Noodles. If you’re lucky, they might not be out of date.

“I cut back on delicacies,” says Cockbain in the matter-of-fact style for which he has become famous in the ultra-running community. “You can get through any of these races with a bit of water and food. I wanted to make it all about the running.”

For Mike Raffan, a 43-year-old IT manager from Aberdeen who finished second in 2021, that’s part of the appeal. “It’s nice that there isn’t any nonsense,” he says. “The Tunnel is pure, unadulterated running. You run from one end to the other in a straight line, turn around a traffic cone, come back again, and just keep going. That’s it.” Persson agrees. “There’s no fanfare. If you’re looking to be pampered, you’ve come to the wrong place.”

All of which adds up to a notoriously low finish rate. Of the 31 runners who started the inaugural Tunnel, only two completed it, and 13 in total in the three years it has been in existence.

“I don’t want there to be no finishers,” says Cockbain. “But I do want them to go through hell to get there.”

So how exactly do you survive a race that is deliberately designed to break you physically, mentally and emotionally?

In one sense, it is simple. “The only things you have to think about are moving, eating, drinking, sleeping and going to the toilet. That’s the limit of your universe,” says Max Newton, a fundraising manager from Sheffield who was among the seven finishers in 2020. “All that jazz in real life is nonsense.”

“One tactic for me is 100% commitment,” says Raffan. Those words carry added weight from someone who ran 182 miles in 24 hours around his back garden three months after open-heart surgery in 2020. During another Cockbain race he continued running in conditions so bleak that his eyeball froze. “I never thought about not finishing the Tunnel. Before the race I told them, ‘Do not let me stop unless there’s a medical reason for it’.”

Mauduit’s approach is similar. “I’m asking myself all the complex questions – ‘Why am I doing this? Should I go there?’ – before the race, in training. During the race I just finish the lap – there’s no question.”

“You have to be all in. If doubt creeps in, you’re gone,” says Cockbain. A 50-year-old electronics engineer by trade, he completed 199 marathons and 106 ultras – including some of the toughest in the world, notably five Spartathlons, three Badwaters, a double Badwater and a 300-mile race in the Arctic – before knee problems forced him to stop running in 2011. “I could sit in a corner and hit my head with a spoon for three days if that’s what I decided to do.”

Bettinson admits the “possibility of failure was a big thing” when he stood on the start line, yet he went on to finish in a scarcely believable 43 hours nine minutes. It remains a Tunnel record by more than six hours and is “up there with some of the all-time greatest ultra achievements”, according to Cockbain, not a man given to hyperbole.

Repeatedly running along the same stretch of tarmac throws up a mental challenge rarely found in races of any distance, let alone 200 miles (the total distance is actually 208 because the tunnel is slightly longer than a mile).

“The difficult thing with doing 100 laps is there are 100 chances to stop,” says 49-year-old Newton, who also ran a 300-mile lapped ultra last summer. Even if runners quit mid-lap, they must make their way back to the start line. Mauduit agrees that the turnaround point at race HQ is often the most difficult. “Once you’re on the course it’s easy – everyone can do two miles,” he says.

“When you reach the start line again you’re facing two choices. One is calling it a day. You will still suffer, your legs will hurt, the pain will follow you for hours, and you have to deal with the fact you gave up. Or you can beat your own personal record in the tunnel and write history. You only have to be motivated for five seconds – just enough time to pick your butt up and get into the tunnel. During the Tunnel I don’t do 200 miles; I do two miles 100 times.”

A positive mindset is universal – some would argue essential – among those who have completed the race.

“When it’s really hurting and I’d rather be in bed, I say to myself, ‘I love this tunnel and I can’t believe I’ve got this opportunity’,” says Persson, a 57-year-old counsellor from Bristol who once ran 900 miles from Land’s End to John O’Groats in 17 days.

“You’ve got to embrace it – there’s no point fighting it or being grumpy. You have to find the bits that make it good,” says Newton. Alan Cormack, who finished second in the inaugural Tunnel, adds: “You don’t have to worry about weather, mud, navigation. And you don’t have to carry a pack.”

With no scenery, music or conversation, surely it must be boring? “On these runs you’re often very busy,” says Mandy Foyster, who staggered over the finish line five minutes inside the time limit in 2021 to become the only female runner to have completed the race. “You don’t have time to get bored – you’re doing maths in your head and you’re so focused on keeping going.”

Persson says “my personality likes routine”, while Mauduit positively loves it. He once ran 238 miles in 48 hours on a treadmill, but says his favourite events are six-day races. His record is 541 miles.

For Raffan, ultras are his meditation. “People ask what I think about when I’m running. Absolutely nothing. At the best points your mind is empty. When you’re in that proper trance state you’re not thinking about anything.”

Running 200 lengths of the tunnel means running 200 times past a speaker built into the wall at the midway point that resembles a giant eyeball and pumps out classical music on loop all day and night. “There are these little submarine-style windows which glow different colours,” says Newton. “It’s like super stereo.”

Cormack describes it as a screeching violin, which Bettinson claims “adds to the weirdness and psychological torture”. Mauduit is more direct: “It drives you nuts.”

More psychological torture comes in the form of darkness. There is only dim lighting in the tunnel – which is shared with cyclists and walkers during the day – and even these are switched off between 11pm and 5am.

“Not only are you in the darkness, but you are alone and you have no headphones. It’s like a giant meeting with you and your feet,” says 47-year-old Mauduit. “All human bodies are conditioned by daylight. In a standard race, when the sun rises you feel great. In the tunnel you have no reference – it’s always night.”

“It became a very big battle to stay awake,” says Foyster, a seasoned ultra-distance athlete whose idea of celebrating her 50th birthday was to cycle between Ben Nevis, Scafell Pike and Snowdon and sleep on the summits of each. “When I got to the end of the tunnel I’d step out in the daylight and just stand there for 10-15 seconds.”

Foyster put more thought than most into keeping the so-called sleep monsters at bay – “I had perfume to spray and a Vicks to stick up my nose – anything to stimulate your senses” – but her most valuable tool was a small spray bottle. “When I felt myself falling asleep I sprayed myself in the face w