What makes Tenby — and Pembrokeshire as a whole — truly remarkable, though, is not just how much the locals want to support it, but by how many want to take part. The town is fond of claiming that thanks to Ironman, it now has more triathletes per capita than anywhere else in the world.

“We think we have the largest percentage of local participation,” Andrew Davies, the town clerk, said. “It is certainly not six degrees of separation: Most people would know four or five people who have done it at least once.”

Davies is not one of them. “I would still be doing the swimming now,” he said, a couple of days after the 17-hour time limit to complete the course had elapsed. But then this is Tenby: Iron Town. It is probably better to say that Davies is not one of them yet.

A Race Saves a Town

The story of Britain’s seaside resorts, over the last half-century, is one of inexorable decline.

The statistics, across much of the country, are grim reading. Blackpool, on the Irish Sea, now has the highest rate of deaths from heroin and morphine in Britain; five more coastal towns are in the top 10.

In 2013, a government study decreed Skegness, a resort on the North Sea coast, the most deprived in England. It was followed by Blackpool, Clacton, Hastings and Ramsgate: all resorts left behind by the rise of cheap air travel and a waning fishing industry.

Clacton, in Essex, is the only place in Britain to have had a member of Parliament from the far-right United Kingdom Independence Party. When that party’s on-again, off-again leader, Nigel Farage, mounted his most recent failed campaign to be elected, he stood in the coastal town Thanet, in Kent, another place ranked among the most deprived in the country.