Pilot Peter Maloney and his female passenger were pulled uninjured from a KC518 Composite Helicopter that crashed and sank in the Hauraki Gulf.
The accident was witnessed by New Zealand navy personnel aboard the nearby warship Taupo and Westpac Rescue Helicopter staff working from their Mechanics Bay base.
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"There was a phenomenally quick response by them and the police as well," St John Ambulance spokesman Norman Ngatai told AAP.
"I'd say they were extremely lucky to crash where they did ... in view of so many (agencies) that could help."
"They couldn't have crashed in a better place."
Witnesses have reported seeing the chopper pause and then lurch on its side into the water in a semi-controlled crash landing that allowed the passengers to escape more easily.
Mr Maloney, a pilot and director of Dairy Flat-based Composite Helicopters, told journalists the controlled landing was "sedate" and "uneventful".
The pair were in the water for less than five minutes before they were collected by personnel from one the Taupo's inflatable patrol vessels, he said.
They were transferred to a police launch before being taken to Mechanics Bay for assessment but Mr Ngatai said they had sustained "very minor injuries" and didn't need hospital treatment.
Mr Maloney had been testing out his state-of-the-art carbon KC 518 chopper at the time of the crash.
