Final answer:
A panicked diver often exhibits erratic movements, distress signals, fearful expressions, and rapid breathing; an abrupt ascent may indicate decompression sickness.
Step-by-step explanation:
The signs of a panicked diver can be subtle but generally include erratic and fast movements, signaling distress such as the out of air signal, wide-eyed and fearful expressions, and fast and erratic breathing patterns. Additionally, a diver abruptly heading to the surface before the scheduled end of a dive can also be an indicator of panic or a problem like decompression sickness (DCS), which can occur if a diver ascends too rapidly and gas bubbles form in the bloodstream. Scuba divers must be trained to recognize and manage these signs promptly to ensure safety.