It happened at 12:30 a.m. Tuesday in the 2500 block of Weymouth Road in Vineland, near Willow Grove Lake.
First responders arrived to find the truck partially submerged and the driver unconscious.
They were able to reach the man, extricate him from the vehicle and get him to the hospital. There was no immediate word on his condition.
It took crews about 6 hours to pull the truck from the water.
Police are working to determine what caused the driver to lose control.