Xibalba

The 2 cave divers you see diving in the real cave were diving with 2 side mount cylinders as well as a smaller cylinder (deco or bailout bottle) and were wearing normal scuba masks, one with helmet with 2 lights on the side (typical cave gear). Yet when you see ALL the divers come up, they are wearing full face masks, only have a single centre back mount tank. They also talk about being low on O2 (not air) and earlier discussed oxygen percentages they had left. It should have been how many PSI or Bar they had left. I'm sure they just took some stock footage of cave divers and put the rest in, but even non divers can tell the difference in gear.

I'm a non diver yet, I know about the use of rebreathers in cave diving. I know there is triple redundancy in safety as cave diving is extremely dangerous. These are the "best" cave divers????? The acting at times was okay. One can only do so much with horrific writing. If you're willing to drop your intelligence level to that of an intoxicated fruit fly, the film is ok.

Subtitles, bad dialogue, slooooooow until the monsters finally show up and then, it doesn't get much better.

This wasn't even enjoyable as bad sci-fi.

It could have been a good movie with a better script. Also the aliens were so stupid looking it could have been a comedy. I don't think saying the aliens were a joke is a spoiler even if they spoiled the movie.

Literally nothing happens for the first 1hr 10. And it doesn't really improve the movie when it does.