... the victim was beyond resuscitation by the time they had the defibrillator attached. Circumstances could not have been more in the victim's favor: a Rescue class, all geared up, having prepared to do an underwater search ...
That illustrates @tbone1004's point rther nicely, unfortunately: middle third of the rescue class is most likely body recovery anyway.
We've an SSI LDS here, they run "React Right" CPR class (incl. oxygen and auto-defib, apparently) and "Stress something" for the recognition and prevention component. So if one wants to learn specifically rescue, those two would be a better option. If the goal is to become a "better diver", I'd look into some sort of intro to tech myself...