High Quality Content by WIKIPEDIA articles! A sea mark, also seamark and navigation mark, is a pilotage aid which identifies the approximate position of a maritime channel, hazard and administrative area to allow boats, ships and seaplanes to navigate safely. There are three types of sea mark:beacons - fixed to the seabed, buoys - consisting of a floating object that is usually anchored to a specific location on the bottom of the sea or to a submerged object. A type of cairn built on a submerged rock/object, especially in calmer waters. Sea marks are used to indicate channels, dangerous rocks or shoals, mooring positions, areas of speed limits, traffic separation schemes, submerged shipwrecks, and for a variety of other navigational purposes. Some are only intended to be visible in daylight, others have some combination of lights, reflectors, bells, horns, whistles and radar reflectors to make them usable at night and in conditions of reduced visibility.

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