Sean O’Connell, the first and only man to swim non-stop around Bermuda, was surprised to learn his unusual feat had been ranked by the 24-Hour Club — a list recognising open-water swims lasting at least 24 hours.

The former Bermuda College maths lecturer was informed by a relative in Ireland, who had searched his name on the internet, that his 1976 open-ocean journey had placed him twelfth out of 89 swims listed.

O’Connell, who completed the 37½-mile feat in a time of 43hr 27min, said he was thrilled that his circumnavigation of Bermuda was still being mentioned almost 39 years after his staggering achievement.

“It was news to me,” admitted O’Connell, whose swim is featured in the Guinness Book of Records and raised thousands of dollars for the Bermuda Physically Handicapped Association.

“I never knew [the 24-Hour Club] existed until a cousin that I’d just discovered in Ireland searched my name on the internet and it came up.”

O’Connell faced several mammoth obstacles during his 22-weeks preparing for the adventure, the idea of which was hatched after “shooting the breeze” with a friend in the Robin Hood over a Friday night pint.

A competent, but by no means exceptional swimmer, O’Connell’s first attempt on July 9, 1976, had to be aborted after it became clear that a strong current was working against him.

He said he remembers moving virtually nowhere in eight straight hours, with his mouth and tongue so badly swollen by the salt that communication with the support boat was rendered almost impossible.

Disappointed, but undeterred, O’Connell, the son of a strict and religious Irish-Catholic family from Brooklyn, made his second and final attempt six weeks later on August 21, when the weather gods were in a far more charitable mood.

“The big thing that killed me the first time were the North Shore currents, which were just too strong,” said the 73-year-old.

“My first attempt was very soul destroying and finally I gave up. I wasn’t even halfway after 35 hours and I knew it was just crazy to try and continue.

“The difficult thing was trying to anticipate the tides which are extremely difficult to predict in Bermuda.

“We opted to put dye markers down at several critical points to see where the current was going, so we could decide which direction I would swim.

“During the build-up, it was very stormy and turbulent and I thought I wouldn’t have a chance. But then the morning of my second attempt the water was dead calm, it was like glass and the dye marker didn’t move at all!”

O’Connell admits that his mind still wonders back to his remarkable triumph and is occasionally stopped in the street by people who remember the extensive publicity that his efforts attracted. “Life is not cluttered with these opportunities and you have to go out and grab them,” he said.

“There was something beautiful about swimming around the Island. No one had done it before and that was the key for me.

“Sometimes I think back and think ‘did I actually do that?’

To mark the 30th anniversary of the occasion in 2006, the Bermuda Masters Swimming Association re-enacted the feat, this time dividing up the gruelling swim into 20 separate legs, with O’Connell completing the final few kilometres to the finishing point at the 9 Beaches Resort in Somerset.