1960s flick The Terror is directed by B-grade auteur Roger Corman, and features the cheesy stylings of a young Jack Nicholson (in a great French soldier outfit) and an old Boris Karloff. Plus kissing in tombs and floating rocks!
Basically, here's the story. Jack Nicholson is fancy French soldier who washes up on an island and is promptly saved and snogged by a hot, giggly girl named Helene or maybe Ilsa. Either she's just an innocent maid, or she's been possessed by the spirit of a dead woman (Ilse) murdered by her husband, the local Baron. And the local Baron is either the Baron or Ilse/Helene's old lover. Plus there's an old witch who is either just an old witch or the mother of Ilse's old lover. Luckily Jack is there to figure it all out by delivering a lot of hammy lines and running around.
He wants to rescue Helene, whom he thinks isn't really Ilse. But Helene, who thinks she really is Ilse, wants to destroy the Baron. Except of course the Baron just thinks he's the Baron, and he's really . . . oh, whatever. Just enjoy this final scene, where everybody jumps in the water in an old tomb and when the walls collapse the rocks start floating on the water. Maybe the rocks just think they are rocks, and they are really styrofoam!
If you're in the United States, you can watch the whole darn movie on Hulu: