He's Nobody's Suitcase
Click to viewPeople don't tend to think about how dangerous a crocodile is, but one is certainly bad enough to serve as a horror movie villain. 2007's Black Water shows this quite well, so well that it remains effective despite a kind of ridiculous third act.
Grace (Diana Glenn) and Lee (Maeve Dermody) are on vacation with Grace's husband, Adam (Andy Rodoreda), and decide to take a boat tour through a swamp. Their boat is capsized by a croc, their guide is chomped to bits, and the three of them are forced up a tree.
The film builds tension nicely and the editing is intuitive as we follow their lines of thought about what the best course of action is. Should they try for the boat, should they try hopping from tree to tree, risking short swims here and there? The croc is fast, appears suddenly, and keeps his victims, and the viewer, guessing about his speed, reach, and location.
Then it gets a little silly. Obviously, not everyone can die right away, or there's no movie, but the reasons the movie gives as to why some people survive a croc attack are pretty flimsy. At some point, it's clear the movie's playing by video game rules. But it never becomes truly bad.