A magician will be restrained, put into a box and lowered into water in the first stunt of its kind by a man from Northern Ireland.
Rodd Hogg will then have three minutes to make his escape in front of hundreds of onlookers before running out of breath.
"I will be handcuffed by the police, nailed into a wooden box, which will be lowered into Portrush harbour by a crane, and then I have three minutes to get out," he explained. "I should be able to hold my breath for three minutes."
The magician will perform the Houdini-esque stunt in front of a busy May bank holiday crowd at 5.30pm on May 28, the day after the popular raft race, and plans to donate any proceeds to charity.
He has never performed the trick with the wooden box before, although he did escape from handcuffs in the harbour a few years ago.
"I am actually nervous - this is not something I can practise every day in Portrush harbour.
"It's only something that I can practise in my head," he said.
"I know how to do it.
"But the box is going to fill up with water very quickly.
"The problem could be the cold - if it affects your thinking and you make a mistake, there is no going back from that."
The former window cleaner switched careers 12 years ago after seeing a coin trick on a night out.
He has since gone on to star in his own Sky TV show, The Irish Magician.