Inside the dangerous, deadly world of IronMan — and the ‘crazy’ intense competitors willing to risk it all just to finish

It took 45 minutes of resuscitation to get Mark Allen’s heart going and save his life.

The then-50-year-old was swimming in the open-water portion of a half-Ironman competition in Georgia, when he went into cardiac arrest.

“I have no memory of what happened,” the Newark, Delaware, financial supervisor told The Post of the 2014 incident. “I had to hear about it from other people.”

And yet, Allen said, he regrets nothing.

“I don’t look back at it like I shouldn’t have done it,” he said. “I would do it all over again.”

It’s that kind of extreme mindset that powers competitors in what is widely regarded as the world’s most challenging race, 140.6-mile-long combination of swimming (2.4 miles), biking (112 miles) and running (26.2 miles) that can lasting 10 to 17 hours.

The Ironman triathlon is also perhaps the world’s most deadly race. Since 2001, at least 85 athletes — an average of more than three a year — have perished while taking part. At one single race in Wisconsin race in 2019, two men died during the swimming portion.

Already this year, there have been two fatalities. On July 12, during an Ironman in Spain, a British man had a fatal heart attack during the swimming leg of the race. On April 18, Brazilian influencer Mara Flávia Souza Araújo, 38, lost her life during the same segment in The Woodlands, Texas.

But that doesn’t stop the weekend warriors addicted to the thrill of the race.

“If you want to do a sport where you’re staying in your limits, you shouldn’t be doing Ironman,” said competitor Jamie Metzl, an author in New York City. “That’s the essence of what Ironman is. The reason why people compete in Ironman is so they can show to themselves that they’re capable of superhuman feats.”

He possessed the mentality and physical drive required to be an Ironman participant. “They are often type-A personalities,” Melissa Mantak, who founded The Empowered Athlete in Colorado and trains people for Ironman races, told The Post. “They’re people who can take on true challenges and have a stick-with-it attitude. They’re not going to give up.”

So much so that, when a June 28 Ironman in France was canceled due to extreme heat, some competitors refused to take no for an answer. One, a 42-year-old man, was killed on the road when he bike crashed with a motorcycle on a portion of the road that would have been restricted to traffic during an actual race.

“We train all year for this. Between the entry fee, transporting our bikes and the hotel, we spent a lot of money,” another rogue competitor on the unofficial course told Triathlon magazine. “We’re here anyway, so we might as well make the most of it.”

The highest number of Ironman deaths, though, happen during the swimming portion, according to a study.

“Two-thirds of the [fatal] events happen during the swim,” said Dr. Kevin Harris, a cardiologist with Minneapolis Institute Heart Foundation who conducted the study on triathlete deaths during ultramarathons, including the Ironman.

He told The Post that it’s likely due to “water temperature, [which is] going to be a shock, the adverse environment, big waves. Marine life has even been speculated.”

Traditionally, crowds also increased the risks.

A complaint filed on behalf of Veronique Tremblay, whose husband died in a 2025 Texas race, alleges that “the sheer number of racers creates a dense vein of participation near the buoys, which causes swimmers to kick and hit each other [unintentionally] to gain an advantage.”

For competitor Metzl, that adrenaline is a bonus.

“I have this strange disposition where the crazier it gets, the more times I get kicked in the head in the swim, the more I think this is really fun,” the author of “Hacking Darwin: Genetic Engineering and the Future of Humanity” said. “What an advantage for me, because I’m not a very good swimmer. But I’m good at getting kicked in the head.”

Ironman has made efforts to increase swimming safety by having competitors start in small groups rather than all at once and by providing lifeguards in water vessels alongside swimmers. According to Mantuk, there are even divers underwater, watching out for swimmers who might be in trouble.

Tremblay, whose husband Jean Francois Alain died while open-water swimming in a Galveston, Texas, race in 2025, is suing the Ironman organization, among others, alleging negligence and wrongful death. She seeks in excess of $1 million.

In an amended complaint filed May 22, Tremblay claims that Alain was “having struggles in the water” and that “underage, rookie” lifeguards did not do enough to keep him safe — saying that “spotting swimmers in distress in this race structure requires extensive training. Defendants failed to so train.”

The Post has reached out to the Ironman organization for comment.

Last July, Sam Buchan also died while participating in the swimming component in Wales. During a March 2026 inquest into his death, his widow, Samantha Buchan, said: “I have serious concerns around the length of time taken for Sam to receive first aid. From the various stories I was told over that day, it took anything from between 10 to 30 minutes to get Sam from the water and to start chest compressions. It appears that the first aid was second to none when Sam made it to the medical tent, but the time it took to get him there would have caused his death.”

The very first Ironman race, held in Hawaii in 1978, was the brainchild of by John and Judy Collins, endurance sports competitors themselves who simply wanted to find the toughest athlete in their realm (hence, combining the three challenges).

It attracted 15 participants. Last year, at races around the world most every weekend, the number went up to 250,000 participants (around 5% do not finish).

Mantuk acknowledged that, for some middle-aged racers — of the 85 deaths, 57 were 40 or older — there is the attraction of challenging mortality and proving what they are still capable of.

“For whatever reason, people don’t feel as fulfilled in their lives as they might want to,” Mantuk said. “There are the endorphins. People feel good when they train. They are often searching for something in their lives when they do a triathlon.”

And while Allen has no regrets, his girlfriend, he said, is 100% against him competing again: “She’s, like, there’s absolutely no way. You have to be crazy. It takes an insane mentality.”

Metzl admits that “Some people say that those of us who do Ironmans are nuts. And maybe they’re right — but there are a lot of positives that come from it. There is risk in everything. Getting out into the world comes with risk.”