Police say they have identified the male driver of a car that went through a roundabout and into Auckland Harbour near the harbour bridge on Tuesday evening.
The man's body was removed from the water, along with the vehicle, about 10.30pm night, police said. His family have been notified and are being supported.
The death will be referred to the coroner, police said.
The car's occupant is presumed to have drowned.
Police and firefighters pulled the submerged car - which was covered with a tarpaulin - out of the water, more than three hours after they were called to the incident, under the bridge near the Curran St onramp from Herne Bay.
'It went straight into the drink'
Auckland student Jack Cameron, 19, was on a run along Westhaven Marina and had stopped to sit down on a seat by the water.
About 7.15pm a car, driving about 30km/h, swung around the nearby roundabout and launched past him into the water.
"A car came around the roundabout and just went straight into the drink," Cameron said.
It was barely 5m from where he sat.
"I looked over and the door opened and I thought they were getting out.
"Then another car arrived and so I was looking at that, then a woman hopped out and said 'Why aren't you in there?'
"So then I looked back and the person wasn't out."
Men on a nearby fishing boat smashed the back window of the car but the vehicle was almost submerged and rapidly went under.
"These guys [fishermen] came over and smashed the back window and that's when I jumped in.
"By the time I got there the car was well gone. I couldn't do anything."
Cameron could see only one person in the silver car when it hit the water, just next to the Harbour Bridge.
He said the water was "cold and murky" when he dived in. "I couldn't see anything," he said.
He was still in wet clothes and wrapped in a towel but he and the men in the boat stayed at the scene until the car was pulled out of the water
"I just want to see the body returned to the family."
'We believe there is one person in the car'
Emergency services were called to the scene at 7.21pm. Earlier Tuesday evening a Fire Service spokesman said three firefighters dived into the water but could not find the car and had handed the operation over to police for a full search and rescue.
"There is a car in the water. We believe there is one person in the car. We have been unable to locate it specifically," he said.
"The call we had indicated there was a car in the water and some people were trying to get the person out of the car.
"Three firefighters entered the water to see if they could find it. They have been unsuccessful."
'It went down so fast, it was gone'
A woman who was one of the first at the scene said she saw a car come through the roundabout at Curran St and head straight for the water.
She was about to head home from walking her dogs when she saw the car plunge into the harbour.
The woman - who did not want to be identified - said she immediately rushed over and jumped in. "It went down so fast, it was gone."
A boat came over and positioned itself close to the car and people on board started yelling at the driver to get out, she said.
"Then the nose of the car started to go down and the rear window was showing, so they smashed it and yelled for someone to get out, and then it disappeared under water."
She was unable to reach the driver or see much in the water.
"I was in there and I could see the lights and the boat was shining torches but it was so murky and horrible it just disappeared."
The whole thing happened so quickly she said, there was "nothing we could do about it".
She was a little shaken up, she said, and feeling "frustrated" that she couldn't do more to help the person or people in the car.
"I was upset," she said, "I'm not a strong swimmer. I wish if I was a stronger swimmer I might have been able to do something."
Police and emergency services were at the scene very quickly, she said. They were "pretty amazing".
"It's very sad really."
Divers worked for hours to find the car, which was pulled upside down from the water just before 10.30pm.
It was partly covered with a green tarpaulin and rolled upright before being dragged it several metres up the bank onto dry land.
Police said inquiries were underway to identify the occupant of the vehicle.