The 47-year-old man was in a vehicle and trying to cross a ford on the Mahurangi River at Warkworth when the incident occurred.
A nephew of the man was with him and was able to make his way to safety.
Police today said additional resources were being deployed into the area today, as water levels had continued to subside overnight.
Police Search and Rescue are carrying out ground-based searching around the banks of the river.
They are being supported by 17 Land Search and Rescue members as well as a water rescue crew from Fire and Emergency NZ.
A police drone is also carrying out aerial searches.
The missing man's wife said her husband had been a fisherman back home in Kiribati.
They moved to New Zealand in 2023 with their four children.
- RNZ/Allied Media
