While formal identification is yet to be completed, the deceased person is believed to be associated with the car that was located in the water earlier.
The total number of occupants in the car and their condition is still unknown.
Emergency services were alerted to a crash on State Highway 8, also known as the Twizel-Omarama Road, in the Canterbury region around 6.50am today.
“Initial information suggests that a car has collided with a bridge barrier and fallen into a body of water underneath,” a police spokeswoman said.
A Coastguard spokesperson said this afternoon that its staff had found the car in the waterway below the Ohau B canal bridge.
Questions about the driver and any passengers were referred to police.
Police said earlier today that they were unable to confirm how many people were in the car at the time of the crash.
Members of the Police National Dive Squad were on their way to the scene and were expected to arrive this afternoon.
One lane of the highway remains closed between Lake Ohau Rd and McAughtries Rd.
Police, Coastguard and Fire and Emergency NZ were involved in the search, and local boaties were providing assistance.
A witness said the car appeared to have crashed into the High Country Salmon farm, just off Lake Ruataniwha.
There were at least four boats on the water searching for the vehicle, they said.
