A man has died while diving at Mathesons Bay near Leigh, north of Warkworth, police say.
The alarm was raised just after 11am because the divers were overdue and should have resurfaced.
The police and St John Ambulance responded to the call.
The man died at the scene, and another was being taken to North Shore Hospital in a moderate condition.
Another man who tried to rescue him also had to be flown to Auckland hospital by helicopter.
There have been at least eight other fatal diving incidents throughout the country since Christmas, four of them in Wellington.
A 37-year-old woman died near Island Bay in Wellington last Monday, and two divers died off Great Barrier Island last weekend.
Meanwhile, the body of a 63-year-old man was found today after what police described as a routine fishing trip that went tragically wrong in Hawke's Bay.