That's bizzare - we totally enjoyed our cave tubing experience. There was probably less than five minutes total time in the caves where you couldn't see some light at one end or the other. Based on our experience, I can't imagine getting "washed" or sucked into anything - it was a slow easy current - about the worst thing that happened to us was the water was shallow in some spots and our guide would yell, "Butt up!" My husband is not a big water fan, but still we had a blast - going again next week - I highly recommend it!
What time of year did you go?