Buoy apparatus and buoy control system for identifying an underwaterobject, and method for identifying an underwater object are disclosed. Abuoy apparatus for use underwater, comprises a buoy securely connected toa first end of a rope； a spool structure securely connected to a second end ofthe rope； a retractable head for engaging the spool structure； and a spoolcontrol device for actuating retraction of the retractable head, , wherein inresponse to an instruction from the spool control device, the retractablehead disengages the spool structure, and the spool structure releases therope when the buoy raises toward a surface of water.
