What is one of the sign markers for indicating distress under water?

Waving both arms above the head is a widely recognized distress signal in aquatic environments. This gesture is highly visible to other divers or rescuers and indicates that the individual is experiencing a problem and requires assistance. It effectively captures attention because it is a clear and exaggerated movement that stands out in the water, where subtle signals might go unnoticed.

Understanding distress signals is crucial for safety in diving. Other options may not convey urgency effectively or could be misinterpreted by fellow divers. For instance, circling in one place might suggest confusion or a lack of awareness rather than an active call for help. Grabbing the air supply could indicate panic or a problem but lacks a clear communicative intent to onlookers. Making a ‘V’ sign could easily be mistaken for a non-verbal communication that doesn't convey distress, as it lacks urgency or recognition.

Thus, knowing the appropriate and widely accepted signals, like waving both arms above the head, enhances safety by ensuring that a diver in distress can be quickly identified and assisted.