Twenty seven people have jumped into icy waters in Wellington - to raise awareness around safer boating.

The number represents how many people died in boating accidents in New Zealand last year.

Maritime New Zealand director Keith Manch says there seems to be a bit of a macho culture where boaties think they'll be fine on the sea.

"The statistics, the actual lives, the people that die at sea, [there's] real evidence that's not the case," he said. "Life jackets should be worn."

"Of the 27 people that died in 2014, around two thirds of those could have lived if they were wearing life jackets."