The Island (1985)
A geography teacher (John Shum) takes 6 of his students on a 2 day field trip to a small, abandoned island off the Hong Kong coast. They soon discover that the island is not quite unpopulated - three brothers live amongst the ruins, and the visitors soon figure out that they might not be entirely sane.
The set-up is basically a typical teen-slasher film, shot through with some DELIVERANCE style redneck misbehaviour. The characters are pretty thinly fleshed out, but the locals are colourful. John Shum's teacher is not somebody you want to depend on in a crisis - well, nobody handles the situation terribly well. The story is plausible enough to provide some genuine tension at times, and the location is used to good effect.