Joseph Parker traded his boxing gloves for a pair of swimming togs today, taking part in the Heart Kids 360 Heart Stopper challenge to raise money for the charity.
Parker is used to taking heat in the middle of the ring but instead spent six minutes in icy cold water to raise money for the Heart Kids Annual Appeal. He raised $43,000 for the charity.
Twelve babies are born with a heart defect in New Zealand every week and it is the number one cause of death in infants and babies.
Joseph Parker said he had a personal connection to Heart Kids because a friend's child was born with a congenital heart defect.
"Getting in the ring with Dillian (Whyte) was nothing compared to this," he said.