The Polar Plunge does that to its participants.
The frigid midwinter temperature of the water at St Clair beach is always much colder than most people expect.
About 500 people, variously dressed as All Blacks, Smurfs, vestal virgins, brides, robots, the Grim Reaper, and even a large piece of seaweed, ventured into the water.
The majority of participants lasted less than a minute, but a few brave - or possibly crazy - stragglers lasted longer than 10 minutes.
It is fair to say, the Smurfs came out of the surf feeling slightly bluer than they looked when they went in.
But for the large piece of seaweed, who only wanted to be known as Sigmund the Sea Monster, the 83rd Polar Plunge was worth the discomfort.
"It's a really good cause. This is the first time I've ever done this.
"There's such a good spirit out there - it's a lot of fun. I'll definitely do it again next year," he said.
About $3000 was raised during the event, all of which would go towards buying an $18,000 inflatable rescue boat for the St Clair Surf Life Saving Club.
Club chairman Antony Mason was delighted with the amount raised, and was just as pleased with the estimated 1500 supporters who cheered on the participants.
He believed it was the largest number of people at the event for many years.
"It's a marvellous effort."
