The driver managed to escape as waves crashed into his upturned vehicle in Buchanhaven Harbour in Peterhead at 8:40am on Saturday.
A coastguard spokesman said: "His life must have flashed before his eyes. We got a call to say a car had gone into the harbour.
"It appears there was a person in the vehicle at the time of the incident but he managed to get himself out of the car very, very quickly." It is still not clear exactly how the car, which was badly damaged in the accident, ended up in the water or where it had come from. Police said the driver had been traced and had not been seriously injured.
A Grampian Police spokeswoman added: "The car was recovered and no-one was injured. There will be inquiries as to how the car got there."
Peterhead councillor Sam Coull said: "I can't imagine why anyone would want to go to Buchanhaven pier with a car at this time of year. Buchanhaven has always had a treacherous cobbled surface. The guy should be congratulated on getting away with his life."