At 0148 hrs the company 3 bunkroom crew was alerted to 245 C Street in Solomons for an MVA. The Chief 3B along with Rescue 3 and Ambulance 38 arrived on location to find a single SUV that had backed over the seawall at a local marina into the water. A single occupant had already been extricated by bystanders prior to our arrival was taken into evaluation by EMS. Command held Company 3 units only as Rescue 3 secured the vehicle till arrival of a heavy wrecker to be used to remove it from the water. Crews operated for approximately two hours assisting the tow company before returning to service.