A buoy is a floating device that can have various purposes, which determine whether the buoy is anchored (stationary) or allowed to drift. In American English it is pronounced [ˈbu.i], while in Commonwealth English (including Canada), the pronunciation is virtually identical to boy ([bɔɪ]). sea mark - aids pilotage by marking a maritime channel, hazard and administrative area to allow boats and ships to navigate safely. lifebuoy - a life saving buoy designed to be thrown to a person in the water to provide buoyancy.