This feels more like a cautionary note than a standard movie review. I’m not going to tell people to avoid seeing it entirely because if this type of film—a teen-slasher sort of thing—is what you're looking for, you’ll likely find it perfectly acceptable. My purpose in writing this is really to offer a heads up, wishing someone had done the same for me beforehand; it would have spared me the unpleasant feeling that lingered afterward. The initial portion of *The Devil’s Mouth* actually rises above what’s typical for movies like this. That's precisely why the latter half was so disheartening. If those first scenes hadn't taken the time to build believable characters, people you could connect with and find engaging, then the letdown later on wouldn’t have stung quite so much. It isn’t a terrible film, mind you. The movie begins with teenagers who manage to hold your attention as they scream, run, and generally react in terror—which is usually why we watch these kinds of movies, isn't it? However, the second half employs a familiar trick. SPOILER ALERT! The narrative pivots from portraying characters desperately trying to escape and survive to suddenly becoming a “let’s fight that shark!” scenario. Why? If you’ve ever found yourself cornered in a cave with an angry bull shark—and who hasn't?—you understand how foolish it is to decide to take on a top predator in its own territory. It's unbelievably foolish. Anyway, appreciate the first half, but be aware of what’s coming. I truly think this warning will enhance your viewing experience by preventing you from feeling misled as I did. I really hope this proves useful; if it does, please tell me so.

Source on TMDB