Isolated danger mark

Examples of Isolated Danger Marks

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.^[1]

Isolated Danger Mark near Hvar, Croatia

Isolated danger marks are recognisable by the following characteristics:^[1][2]

• 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

• Geography portal

• Navigation
• Lateral mark
• Cardinal mark
• Safe water mark
• Special mark
• Emergency wreck buoy
• Light characteristic

Footnotes

1. "R1001 The IALA Maritime Buoyage System". International Association of Marine Aids to Navigation and Lighthouse Authorities. Retrieved 2025-07-09.
2. "R0110 – Rhythmic Characters of Lights on Aids to Navigation". International Association of Marine Aids to Navigation and Lighthouse Authorities. Retrieved 2025-07-09.

References

• International association of maritime aids to navigation and lighthouse authorities (2010). "Maritime buoyage system and other aids to navigation" (PDF). IALA-AISM. Retrieved 11 August 2019.
• Service Hydrographique et Océanographique de la Marine (1 September 2016). Signalisation Maritime (PDF) (in French). France: SHOM. ISBN 978-2-11-139457-5. Retrieved 11 August 2019. {{cite book}}: |work= ignored (help)