Police said they were informed of the death about 7.45am and on Sunday confirmed the circumstances had been referred to the Coroner.
An announcement was made on social media soon after the kaumātua discussed the matter, saying it related to all water activities within the area.
It affected the IronMāori swim, but a sailing regatta further out to sea was able to go ahead.
In an emotional statement on the IronMāori Facebook page said it was “absolutely heart-breaking to have a participant pass at our event, as they all become part of our wider whānau.”
“Firstly our hearts go out to the whānau, we send our aroha and heartfelt sorrow to each and everyone of you at this very sad and tough time,” it said.
The organisers thank the Surf Life Saving team, the swim director and marshals, event medics, emergency services and all others who helped and supported the “team,” and kaumātua who guided the tikanga.
They also thanked all participants for accepting the decisions that were made.
“They were not easy ones to make,” they said. “However we know they were the right ones, so we are truly thankful for the way you received them.”