Xibalba

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

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.

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.

As with most movies, the last twenty minutes are where the good stuff happens and things are wrapped up. In this case, the last twenty minutes got a bit confused. There was a definite conclusion and it seemed to fit the rest of the story, but it had more potential and it left a lot of questions unanswered.

Things got weird in a hurry and then sort of slipped into another movie.

In any event, the acting was pretty decent and nobody got too melodramatic until the last few minutes. The scary guys were a bit weird and overdone. The ultimate ending was a bit odd and there was no explanation as to why the other players couldn't do whatever by themselves.

If you can see it for free, it's not too bad.

It's definitely a SyFy Channel wannabe, but actually with a far better plot and cinematography. The biggest con is it takes forever to truly get to the action with the "aliens". While the build up is decent it lacks energy. The direction and story building is there but the actors for the most part seem to just go through the actions. The fact that the build up takes so long and you invest in watching for a payoff the payoff comes slate and leaves the movie open as if this were a pilot or the beginning of a series of movies and with the premise used. Sadly, because of that the ending was empty as a standalone.