Police say an officer put his life at risk to rescue a person near death who has spent about 20 hours in the sea with three relatives.
A teenage boy and a man in his 30s are in Auckland Hospital in a stable condition, while an 11-year-old boy remains missing after their small boat capsized shortly after leaving Kawakawa Bay on Thursday morning.
The family members from Papakura left the bay at 11am on Thursday, but their runabout got into trouble about an hour later. Police say none were wearing lifejackets - even though they had them on board.
The group, aged between 11 and 39, was reported missing just after midnight on Thursday, prompting an unsuccessful aerial search.
Three people were rescued on Friday morning after spending about 20 hours in the water between Waiheke Island and the Coromandel. A yachtie found the upturned vessel and plucked one person from the sea, while another was winched to safety by rescuers.
Police said their Eagle helicopter spotted a third person in the water and rescuers believe that he was near to death. They said an officer put himself in danger by entering the water to wait with him until they could be picked up by a police launch.
Inspector Shawn Rutene told Radio New Zealand's Checkpoint programme on Friday when the police helicopter found the third person he was in a bad way.
"They could see him bobbing in the water - his arms were up, but he was actually what they considered to be near death. So they made a decision to put one of their crew on the back of the helicopter into the water. That's quite a dangerous thing to do, but we managed to do that."
The 11-year-old boy drifted away from his family at 2am on Friday and hasn't been seen since. Coastguard operations manager Ray Burge says the fact he wasn't wearing a lifejacket means his chances of survival aren't good.
"Because it's only a 12-foot vessel, which is relatively small to have four people in it and the conditions are not perfect out there - there is a significant amount of wind - I would say small vessel, overloaded, no lifejackets equals tragedy."
Inspector Rutene said police and other emergency services are very frustrated that people continue to go out on the water not wearing lifejackets.
"I don't know what more we can do. There's been enough information put out there and we have been pushing hard for people to realise the dangers and they should wear their lifejackets."
Police called off the search for the boy on Friday evening and are considering if they will resume.