lifebuoy - a life saving buoy designed to be thrown to a person in the water to provide buoyancy. Usually has a connecting line allowing the casualty to be pulled to the rescuer
Submarine communication buoy - to be released in case of emergencies or for communication
Communication buoy for a bottom pressure sensor, for tsunami detection.
shot buoy - used to mark dive sites for the boat safety cover of SCUBA divers so that the divers can descend to the dive site more easily in conditions of low visibility or tidal currents and more safely do decompression stops on their ascent
mooring buoy - to keep one end of a mooring cable or chain on the water's surface so that ships or boats can tie on to it
tripping buoy - to keep one end of the tripping line on the water's surface so that a stuck anchor can more easily be freed
mattwunderle: RT @Buoyalarm: Kauai Buoy (@Buoy51001) just popped at 19 seconds. Looking good for the Reef Hawaiian Pro at Haleiwa tomorrow. http://bit ...
capegirlindc: @caffeinatedpaul Thanks! Patty says she has retrieved another Buoy for you.
iembot_pqr: #PQR: 23 W Yaquina Head [Pzz275 Co, OR] Buoy reports NON-TSTM WND GST of M62.00 MPH at 12:00 AM PST -- southwest http://tinyurl.com/yz6symw