What should divers use to indicate their presence in the water when civilians are nearby?

The sport diver flag is the appropriate indication for divers to signal their presence in the water, especially when civilians are around. This flag, commonly recognized as a red flag with a white diagonal stripe, is specifically designed for recreational divers. Its purpose is to inform boaters and other watercraft operators that divers are present in the vicinity, thus promoting safety and awareness.

Utilizing the sport diver flag helps to clearly communicate that there are divers underwater, reducing the risk of accidents such as boats coming too close to a dive site, which is crucial in populated or busy waters. This flag is typically displayed at the dive site or on the surface while divers are submerged.

In contrast, other flags mentioned, such as the alpha flag, while also used for indicating diver presence, are more aligned with commercial diving operations and may not be as easily recognized by civilians. The flag of convenience does not serve a safety function and is not recognized for signaling diver presence. The commercial diving flag is designated for professional operations rather than recreational diving and might not resonate with the general public in the same way as the sport diver flag.