The term "diver down" refers to a safety flag used by divers to indicate their presence underwater. This flag is typically red with a white diagonal stripe and is displayed on the surface to alert boaters and other watercraft to the nearby diving activity. The flag serves as a warning to maintain a safe distance, helping to prevent accidents. When a diver is submerged, the "diver down" flag is essential for safety. It is recognized internationally, and its use is governed by various maritime laws. Proper display of the flag ensures that divers can explore underwater environments, such as coral reefs or shipwrecks, with reduced risk from passing vessels.