A young woman has escaped with minor injuries after Busselton police rescued her from her sinking car, which she had crashed over a retaining wall. 

Two officers were on patrol around 1.15pm Friday when they were flagged down by a member of the public on Layman Road in Geographe, police said.

They were told a Ford Falcon sedan had crashed over the edge of a retaining wall, run down the embankment and was sinking, with the 25-year-old driver trapped inside.

One officer called for assistance while the other jumped and swam out to the car.

He smashed the rear window with his baton before pulling the woman to safety.

She received minor injuries and was treated by St John Ambulance officers.