12The Descent (2005)
Spelunking is insane and no one should do it—especially in horror movies, where you’re bound to run into anything from cannibalistic former friends (pretty good, all things considered) to horrifying rat creatures who treat you like a Meals on Wheels (this is the worst-case scenario). The Descent features a group of women going caving, and it’s hard to think of any other movie that works so completely as an anti-tourism ad. It’s already an activity that places you deep into the cold, dark ground with no ability to call for help, and that’s all before they run into a group of creatures that look like a gross mix of mole rats and vampires.
Part of the horror of The Descent is the darkness and enclosed space that the characters are trapped in, but the few glances of the creatures that viewers get is enough to know that they don’t want to be anywhere near these horrible things. The creatures’ ability to navigate the terrain so smoothly and with such immediately predatory behavior helps establish that this is not a place anyone wants to be. Moral of the story: stay out of holes in the Earth.