A buoy (/bɔɪ/, North America more commonly, but not exclusively /ˈbuːi/)[1] is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. The etymology of the word is disputedRace course marker buoy – Buoy racing is the most prevalent form of yacht racing and power boat racing. The buoys are used to delimit the race course and must be passed to a specified side. Course marker buoys are also used in underwater orienteering competitions.Emergency wreck buoy – An Emergency Wreck Buoy provides a clear and unambiguous means of marking new wrecks. This buoy is used as a temporary response, typically for the first 24–72 hours. This buoy is coloured in an equal number of blue and yellow vertical stripes and is fitted with an alternating blue and yellow flashing light. This has come about due to the collisions which occurred in the Dover Strait in 2002 when vessels struck the new wreck of the MV Tricolor.[3]Ice marking buoys – used for marking ice holes in frozen lakes and rivers, so that snowmobiles do not drive over the holes.Large Navigational Buoy (LNB or Lanby buoy) is an automatic buoy over 10 m high equipped with a powerful light monitored electronically as a replacement for lightships.[4] A LNB may be marked on charts as a Superbuoy.[5]Lateral marker buoySafe water mark or Fairway Buoy – a navigational buoy which marks the entrance to a channel or a nearby landfallSea mark – aids pilotage by marking a maritime channel, hazard and administrative area to allow boats and ships to navigate safely. Some navigational buoys are fitted with a bell or gong, which sounds when waves move the buoyWreck buoy – a buoy to mark a wrecked ship to warn other ships to keep away because of unseen hazards.Light buoy - a buoy to use as demarcation at night.