Alcohol and speed are thought to have played a part in a crash in which a speedboat smashed into the back of a yacht.
After colliding with the yacht in West Auckland late on Saturday night the speedboat flew through the air before hitting a wharf and sinking.
Maritime New Zealand says a family was on the yacht and two of them tried to rescue the speedboat's two occupants.
The Coastguard says it pulled four people from the water after the accident at Herald Island, near Whenuapai, and the man and woman who were in the speedboat were taken to hospital.
The woman is in a stable condition and the man was discharged on Sunday.
The Coastguard says only one person was wearing a lifejacket and there appears to have been no radio on board.
Police and Maritime New Zealand are investigating.
