The Matanzas River is a body of water in St. Johns and Flagler counties in the U.S. state of Florida. It is a narrow saltwater bar-bounded estuary sheltered from the Atlantic Ocean by Anastasia Island. Three major bridges cross the Matanzas River: the Bridge of Lions and the Mickler-O'Connell Bridge carrying Florida State Road 312 between St. Augustine and Anastasia Island, and the Crescent Beach Bridge (Verle Allen Pope Bridge) carrying State Road 206 across the river to Crescent Beach.