A man in his 20s was apparently driving on Lemon Street at about 5 a.m. when he failed to stop at a waterfront dead end and drove into the river, according to Vallejo police.
The man was not injured and evacuated himself from the vehicle, which was stuck in water around four feet deep, police said.
It was not immediately clear if drugs or alcohol were factors in the crash, police said. The suspect was not cooperating with investigators.
The U.S. Coast Guard responded and did not detect any significant fuel leaks from the vehicle.
The incident remains under investigation.