Delaware law requires scuba divers or snorkelers to display a flag to mark their diving area. Vessels not engaged in diving should stay well clear of areas displaying the “divers” flag or vessels displaying the “Alfa flag.”
Scuba divers and snorkelers should not place a flag in an area already occupied by other boaters or where their diving operation will impede the normal flow of waterway traffic. Divers also should follow all of the water safety rules themselves.
Two types of flags are used to indicate diving activity.
Divers Flag: A rectangular red flag with a white diagonal stripe is displayed from a float during diving operations.
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.