Looks like Rumbling Falls Cave here in Georgia. I gotta tell ya, shooting in a cave is pretty darn hard to do. Especially the big room shots. I've done a bit and I've never been able to get enough light together to light a large room. They still use flashbulbs for that kind of work, electronic flash is a bit dangerous in that damp environment for really high power levels so you don't see too many people doing it.