I honestly cannot believe that someone could read about this near-accident, and STILL write, "Cavern diving is not that dangerous."
What is truly appalling about this incident was that the father in this family was an OW instructor -- and when they were warned, by people on the site, not to enter this cave, the response was, "It'll be OK; he's an instructor." In fact, it apparently wasn't until two of the family exited and it was realized the girl was lost, that anybody seemed to get wound up about it.
I have been in zero viz -- it was intentional, as a training experience. I wasn't frightened, because I actually had a fair amount of blackout mask time by then, but it is quite different to be in opaque water, than it is to have your lights off or your mask blacked out, where you know in the back of your mind that, if you got into real trouble, it would only take the click of a switch to get out of it. But I have seen an OW diver, doing his cavern class, fail and bail over the inability to do a mask-off swim. NONE of the skills required to cave dive safely is beyond the grasp of an OW diver who is willing to take the time and make the effort to learn them (although the temperament to cave dive safely is not that common). In fact, a lot of them make OW diving much more fun, like learning non-silting kicks.
But I think we DO need to harp on this stuff, because people keep DOING this -- and clearly, in this case, the thought process was, "I'm a dive instructor, I'll be fine." OW instructor training -- even if it's good, and it isn't always -- has NOTHING to do with diving overhead environments, far less GUIDING people into overhead environments (which this father was, in effect, doing, since he had the most training of the group).
I ride horses, which is a sport in which people get killed and maimed on a regular basis. Some behaviors in riding are viewed as foolish -- one is riding without a helmet. There has been a diligent effort to educate people about helmet use, and if a magazine publishes a photo of a rider without one, you can guarantee that that magazine will receive letters of complaint. Those efforts HAVE borne fruit, in that rules have been changed in competitions to allow helmets where they were not allowed before. One can only hope that the efforts people make here, to write about the risks of entering overhead environments and to post stories like this one and the death accounts, will have an effect -- not only to make the individual diver decide not to enter a cave, but perhaps more importantly, to encourage some OW instructors to make a greater point of teaching their students not to do it.