Persons scuba diving, skin diving, snorkeling, or underwater spearfishing must display a diver-down flag to mark their diving area.
- A diver must stay within 75 feet of a diver-down flag.
- No person may place a diver-down flag in such a manner that the flag restricts watercraft navigation.
- Vessels not engaged in diving operations must stay at least 75 feet away from any displayed diver-down 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, at least 12 x 15 inches in size, with a white diagonal stripe is used in South Dakota to indicate diving activity. The flag must be clearly visible and securely attached or anchored to a float, a rubber tube, or a boat.
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.