The Coastguard says none of four people aboard a boat that capsized near Motuihe Island in the Hauraki Gulf on Saturday morning was wearing a lifejacket.
The incident follows the fatal capsize of a boat in the Firth of Thames on Thursday. Three survivors, all relatives, were rescued on Friday morning after more than 20 hours in the water but a boy of 11 (not 13, as previously stated by police) is still missing.
There were lifejackets aboard their boat but no one was wearing one.
Coastguard spokesperson Georgie Smith says in the latest incident four people not wearing lifejackets were thrown from their small boat after a wave struck.
She says a member of the public helped them and all were safe by the time the Coastguard arrived.
She says the Coastguard cannot stress enough the importance of not just taking lifejackets on a boat trip but wearing them, especially on smaller boats.
The search for the boy missing after Thursday's accident, between Waiheke Island and the Coromandel Peninsula, is now a body recovery process.
The Navy has been using a specialist underwater device to trawl the Firth of Thames for his body. A torpedo-like device can take pictures while running unattended along the seabed.