A couple managed to escape as their parked car rolled off Birkenhead Wharf and into the water last night.
The pair were about to go for a walk when their vehicle careered down a slope around 9pm and "went into the tide", Inspector Willie Taylor said.
It is believed the couple were in the car initially, but managed to get out before it went under.
Mr Taylor said the pair were not badly injured, "just embarrassed".
The car was believed to be a Nissan Bluebird.
It was pulled from the water by a tow truck later in the evening.
Although it was not clear what caused the car to roll down the hill, Mr Taylor said it was suspected that the handbrake had been left off.
In February, two constables helped rescue a woman from her sinking vehicle at the nearby Fisherman's Wharf on Northcote Pt. As two members of the public tried to hold the car, Paul Watts smashed its back window with a rock and he and Simon Russell pulled the woman to safety. The four were later commended by NZ's top police.
