An Isolated Danger Mark, as defined by the International Association of Lighthouse Authorities, is a sea mark used in maritime pilotage to indicate a hazard to shipping such as a partially submerged rock. Isolated danger marks are recognisable by the following characteristics:

• Generally a pillar or spar shape, but could alternatively be any other shape as long as the shape is different from those used for lateral marks.

• Coloured black with one or more broad horizontal red bands.

• Always having a topmark attached which is two black spheres stacked vertically.

• If a light is fitted, it is white in colour and has a light characteristic of group flashing 2 (abbreviated as "Fl(2) W"). Two flashes of white light in succession are followed by a longer duration of darkness.

See also

• Navigation

• Lateral mark

• Cardinal mark

• Safe water mark

• Special mark

• Emergency wreck buoy

• Light characteristic

Footnotes

References