All wrapped up in the action of the ending... *spoilers*

that I forgot about the hallucinating.

At first I thought Lisa was hallucinating her sister's voice when she was still in the cage, but that everything else was really happening. I expected her to swim up to Kate's mutilated body and be shocked back to reality.

Then I forgot about it because the swim up to the surface and the attacks were very gripping!

Great great movie, I liked it more than The Shallows.