A panic attack does not necessarily result in panic disorder. For it to become a disorder the attack will be followed for a period of one month or more by at least one of the following: constant worry about another attack, constant worry about the cause of the attack, major behavioral changes. All of which lead to subsequent attacks that could worsen if untreated. This is a brief and incomplete outline. Found this through some research on this subject.
I think there is a general misunderstanding about what panic is, I admit I understood panic to mean an out of control response or irrational reaction, which includes freezing, to a stressful situation. But in medical terms a panic attack seems to be a high anxiety experience where a level of rational control is maintained, if diminished.
You make some interesting points Scuby Dooby, about people with panic disorder diving as long as the trigger for the attacks is not SCUBA related. While these people who have learned to recognize and control their anxiety may have an advantage over someone who has not, with or without this disorder, they probably remain more likely to experience a panic attack underwater (?) then someone who doesn't have this condition. And a panic attack places everyone closer to the edge of all out panic.
I would imagine someone with this codition should be extra cautious in selecting the dives they do and how they do them.
Stop, more like a pause, and Breathe in and out a few deeper breaths to demonstrate we remain in control of ourselves. This has a calming, relaxing effect which enables us to Think more clearly and gives us the confidence to Act more decisively.