According to the Delaware City Fire Company, crews responded at about 11:45 p.m. to the Chesapeake & Delaware Canal in the area of the Reedy Point Bridge for a sinking vehicle.
Rescue swimmers were initially unable to find the vehicle because it was too deep, but its location was confirmed with sonar.
The vehicle was about 12 feet underwater and dive rescuers were deployed, officials said.
Crews said the divers battled near-zero visibility and a strong current, but they were able to locate the vehicle and remove a person.
Despite lifesaving efforts, officials said the person inside the car was pronounced dead on scene.
Delaware State Police are investigating the incident.