Isolated danger mark

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]

Examples of Isolated Danger Marks
Isolated Danger Mark near Hvar, Croatia

It is recognisable by its black and red bands and top-mark of two black balls.[1]

Its distinctive sequence of flashing white light consists of 2 quick flashes in intervals of either 5 or 10 seconds.[2]

See alsoEdit


  1. ^ a b IALA 2010, section 4.
  2. ^ SHOM 2016, section 1.2.4.


  • 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). Ouvrages Généraux (in French). France: SHOM. ISBN 978-2-11-139457-5. Retrieved 11 August 2019.