Scuba divers or snorkelers must display a diver-down flag that marks the diving area. Vessels must remain at least 100 feet away from the person in the water.
Two types of flags are used to indicate diving activity.
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.