Hmm...could be really interesting, I work at a ride like that and lately I'd been thinking about how such a thing would make an interesting "dungeon" setting. Especially with a "boat" style ride, where the PCs would be wading through waist-high water.

I can actually see a lot of possibility for some really nice traps and interesting terrain hazards with a map like that, as well as it being just thematically fun to mess with, say, an old derelict carnival ride that's infested with monsters or something.