State law requires that scuba divers or snorkelers display the diver-down flag to mark the diving area. Vessel operators must not operate within 200 feet of a displayed diver-down flag. Two types of flags are used to indicate diving activity.
A rectangular red flag at least 12 x 12 inches with a white diagonal stripe if on Vermont waters.
A blue and white International Code Flag A (or Alfa flag) if on federally controlled or international waters.
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.