Hawaii law requires that scuba divers or snorkelers display a diver-down flag to mark the diving area. Vessel operators must not operate within 50 feet of a displayed diver-down flag on navigable streams or within 100 feet of a displayed diver-down flag elsewhere. Divers must not surface more than 100 feet away from their flag in ocean waters or 50 feet away from their flag in navigable streams. Two types of flags are used to indicate diving activity.
In addition to the red-and-white flag, a blue-and-white International Code Flag A (or Alfa flag) must be displayed on vessels on state waters.
Divers Flag: A red flag with a white diagonal stripe must be displayed on the highest point of the main structure of vessels on Hawaii waters so that the flag is visible from all directions. This flag indicates the presence of a scuba diver or snorkeler in the immediate area.
- For non-motorized vessels that are 16 feet or less in length, the flag must be at least 12 inches x 12 inches in size.
- For all vessels that are more than 16 feet in length, the flag must be at least 20 inches x 24 inches in size.
Alfa Flag: A blue and white International Code Flag A (or Alfa flag), at least 3.3 feet (one meter) high and visible from all directions, must be displayed on vessels on federally controlled waters. This flag indicates that the vessel is involved in a diving activity.