Piranha 3D (2010)

In a small town, an underwater tremor frees a school of prehistoric man-eating piranhas just as thousands of partying teens begin arriving for Spring Break on the lake. Sheriff Forester (Elisabeth Shue) heads out with a team of scientists (led by Adam Scott) to figure out what's going on. Meanwhile, her teenage son, Jake (Steven R. McQueen), is supposed to be watching his younger brother and sister. But instead, he's accepted a job working for a porn director (Jerry O'Connell). These characters and others find themselves stuck in the water as the vicious fish begin their relentless attacks. Can the sheriff find a way to stop the fish and save the town?

The movie does veer into some very mature territory, killing the mood with a particularly horrifying post-carnage scene in which wounded, half-devoured teens limp out of the water, bones and blood and hanging flesh on display. It further crosses the line when one cowardly teen tries to escape and runs over several people with his motorboat. And then there are the two small children who get caught up in the fray... But aside from these moments, Piranha 3D is generally out for a good, gruesome time, and it mostly delivers.