I think it is time we retire our old friend the North American Dive Flag unless displayed from a boat. As most divers know, boaters often see the red & white diver down flag as a slalom marker and drive over it as if on a poker run. I propose divers who tow the flag replace it with a plastic version of the floating log seen here. Boaters hate having to replace broken props and pins and are on the lookout to avoid hazards which may damage their boats. The floating log will surely create a wide berth keeping divers safer than our current methods (bird not included). 
