I enjoyed this movie. I should also say that I saw it 3D, which did not deliver the same kind of 3D effects as other movies like Avatar. That being said, the 3D was particularly good in the cave diving scenes and really gives you the feeling that you are there with them. This was worth the price of admission for me.
I think one has to come to terms with the fact that this is a Hollywood, blockbuster-type of movie that is intended for huge audiences, most of whom do not dive. But even that being the case, they lingo they used, the training they discussed, the equipment they used, were "pretty much" spot on from what I understand of cave diving.
Yes, it was predictable at some points (right away, I wondered when the necklace flashlight would end up saving someones life,) and perhaps took artistic liberty with the plot. But, I think they did a pretty good job with the movie overall. And, although it had a (somewhat,) happy ending, the film as a whole was dark and brutally showed the dangers of cave diving. I appreciated that effort to keep it real.
I think the most disturbing scene was the OOA in the huge cavern. As someone who's never used a full face mask, I'm curious as to whether anything else could have been done for that woman. Is FFM air sharing even a realistic solution? I cannot even imagine buddy breathing with a FFM.