"IT ACTUALLY started at a cocktail party, held by the lifeboat coxswain on Christmas Day, 1968," said former GP Ian Wort.
"It was a glorious day and someone said, 'I bet you wouldn't go for a swim in the harbour'."
And so began Coverack's annual Christmas Day charity swim. Last year, more than 160 people took to the water.
Since it began, it has raised an enormous £212,327.67 for Cancer Research UK.
This year, some have questioned why the event has become formal – people have been asked to register and raise £50 sponsorship.
Dr Wort said this goes against the fun and spontaneous element of the day.
He and his friend, the late Derek Carey, took that first plunge and won £10 in the bet.
"We couldn't keep the money so we decided to give it to Cancer Research," said Dr Wort, who still lives in Coverack.
"It was 12.30pm. That's why it's always been held since at the same time.
"Over the years we had all sort of fun, like fancy dress. To see how many people take part now, it's magnificent.
"The only thing I regret is I must have ruined so many Christmas lunches over the years."
Dr Wort took part in the swim each year for 25 years before calling it a day.
This year, the organisers have said no one will be turned away if they haven't got sponsorship or are registered.
Committee chairman Carol Lawrence, who has led the swim for many years with David Philpott, said the £50 was a suggested amount and they currently have no way of contacting the people who take part.
Ann Maree James, of Cancer Research UK, added: "It's an incredible effort by the local fundraising team.
"They don't just raise money at the swim, although this is by far their biggest, but they also raise money from all kinds of events the whole throughout the year. We can't thank everyone enough who supports this event."