The police say the occupants of a car that sank in the Waikato River had been racing just before they crashed.
The driver and his two passengers crashed into the river from Great South Road near Ngaruawahia at about 2.20am.
Police said the driver and two passengers were able to free themselves before the car sank and were not injured.
A second car crashed into a fence nearby and Acting senior sergeant Dale Smith said it appeared the two cars were racing before they crashed.
He said both drivers were over the drink-drive limit.