a fluid discharge apparatus adapted to discharge a cavitating stream of pressurized liquid along with the selective discharge of a secondary material , such as an abrasive , for removing dirt , debris , barnacles , marine growth , and other substances from submerged surfaces is provided . more particularly , the invention contemplates a introducing a pressurized liquid into a cavitation generating chamber to create and discharge a cavitating stream , and a secondary inlet for injecting abrasive material , such as silica , into the chamber to improve cleaning effectiveness . the gas bubbles within the cavitating liquid stream that essentially explode upon impacting debris resulting in tremendous pressure fluxuations provides improved effectiveness in removing debris and aquatic growth from the submerged surface . the combination of a secondary substance , such as an abrasive material , foam , or compressed gas enhances cleaning effectiveness . the invention further improves upon the control of such devices with controls , such as a pistol grip or rotational grip controllers , that allow the diver / operator to adjust flow rates and thrust without releasing his grasp . an improved hand - held apparatus is disclosed with a pistol grip and trigger actuator , and an improved wheeled vehicle is disclosed with improved control handles adapted to actuate valves and closure ports .