We booked cavetubing through Cave-tubing.com. AWESOME, AWESOME, AWESOME. Carnival passengers who booked through the ship paid double the money for 1/2 the tubing time. There is a reason for this because someone apparently died on a Carnival tubing excursion a few years ago, so it's very restricted. Our tour guide was awesome. I never feared for me or my children, and they treated us RIGHT.