Diving operations

Any vessel with divers operating from it must always display signals by day or night to inform other vessel users.

A five knot speed limit applies to vessel operators and water skiers within a distance of 100 m of a vessel, buoy or structure on which a ‘diver below’ signal is displayed.

Five knot sign plus dive signals


Divers should make themselves visible to boaters with the appropriate day flag or night signal. Consider bright clothing for higher visibility. Avoid areas of high vessel usage and areas where the terrain might inhibit vessel operators’ ability to see you in the water.

Day diving: White and blue International Code Flag ‘A’

Vessels under 10 m: Display dive flag at least 750 mm long and 600 mm wide.

Vessels longer than 10 m: Display dive flag at least 1 m. It should be placed to ensure all-round visibility.

Night diving: International signal for a vessel restricted in its ability to manoeuvre

Vessels must show at least three lights in a vertical line, with the top and bottom being red and the middle one white, only where the size of the vessel makes it impracticable to exhibit the lights and shapes otherwise required.


Other vessels

Be aware that divers in the water may not be near a vessel. A diver who is not operating from a vessel that is displaying a dive flag will be attached to a buoy that has a dive flag attached to a rigid replica of the flag.

A master of the vessel must not operate at a speed exceeding 5 knots within 100 m of a vessel or a buoy on which a dive flag is displayed. Divers may ascend at any time.

Divers in a boat with flags Flag on a buoy in water

Pictures supplied by NSW Maritime

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