"It's the height of a power pole," he said.
"Probably at least four or five metres. It's quite a deep little creek."
A man who lives in the area, James McKay said his daughter-in-law had heard the bang of the crash.
It was the first fatal crash in the area that he knew of.
"There could have been the odd minor one that you never hear of, but there hasn't been a fatal one," he said.
Acting Traffic Sergeant Shayne Nolan said police could not confirm the name of the crash victim, but said the incident was "serious".
There was only one vehicle involved and the man was the sole occupant of that vehicle.
Te Ore Ore Bideford Road is closed from Masterton Castlepoint Road to Mangapurupuru Road, while emergency services work to extract the car from the river below. Diversions are in place.
Nolan said the road would be closed for "a couple of hours" while the Serious Crash Unit investigated.
