Having been an employee at the float trip, I seem to remember the original cave was made out of plywood and the rocks were just put at the entrance and exit to make it look like a cave. But you're right, from above, it almost did look like it was made from shabby little buildings. I remember that heavy black plastic was used at points, probably for waterproofing and to prevent light leaks, but it was there and did a good job from 1969 through the mid or late 80's or so whenever it was deemed too old to use anymore and was replaced. It's just too bad the cave there now is not "decorated" better. I think they cut too many corners to build it, and it is rather bland. The pumps for the ride were hidden behind the fake rocks, too. It was funny to go out in the fall and scrape leaves off the filters in front of the pumps, and to suddenly "pop up" from behind a rock as a boat passed by. I scared many a person doing that. After a big scream, everybody laughed til their sides split.
