Police are trying to find a man who rescued a driver when her car ran off a road and into the waters at Tascott on the New South Wales central coast on Sunday.

Investigators say a 20-year-old Ettalong Beach woman was distracted by a flying insect when her vehicle veered off the road, went over a wall and landed in the water on its roof at about 7:30pm.

An unknown man dived into the water to pull her out of the car and onto the shore.

Ambulance crews arrived and the woman was taken to Gosford Hospital as a precaution.

By the time they arrived the man had disappeared.

Inspector George Bradbury says the mystery rescuer should come forward so his bravery can be formally recognised.

"He's saved this young lady's life," he said.

"Obviously we'd like to talk to him so if he's out there somewhere we'd like him to contact Gosford Police Station."

The rescuer, or anyone with information about him, can contact Gosford police via Crimestoppers on 1800 333 000.