Used to signal that a vessel has diver(s) underwater , the red and white flag, created in 1956 by Navy veteran Denzel James Dockery is required by law or regulation in many US states, Canada, and some other countries (e.g. Italy). Regulations require divers to display the flag while diving and to stay within a specified distance of it when they are near the surface. There may also be a larger zone around the flag where no boats are allowed to pass. Can be placed on a boat or on a surface marker buoy.