My husband and I and a couple of friends took a cave tubing trip last year and I don't think we'll try that again. The tubing on the river was fun, but going thru the caves was extremely tense. Our guide kept yelling you must stay against the wall, it is very dangereous and you could get washed into an underground river. And if you did you probably would not live thru it. He has us so scared, we just wanted OUT of the caves!!!
But like I said, the tubing on the river was fun, we just didn't like the dark caves.
But it just might be your cup of tea, if so, stay close to the walls!