As cruise ship passengers destined for Belize City, we booked a tour with Charlie (http://charliescavetubing.com/index.html) through http://www.ecotoursbelize.com/. Charlie was standing where our tender docked even before we pulled in, holding a sign with our name on it. I'm so glad we went with him, instead of the ship. He was professional, knowledgable, and fun, and never once did we feel unsafe.
At the time of booking we requested an additional hike be added on to our regular cave tubing tour. For a small additional fee (still WAY cheaper per person than tours through the ship) we got a phenomenal tour unlike anyone else that went cave tubing that day. For one thing, our tour was private: just the three of us and Charlie, our extremely knowledgable guide. Charlie explained lots about Mayan traditions, and flora and fauna of the rainforest during our hike. It wasn't long before we'd gone far past the wide, perfectly groomed pathways, and past the place where the rest of the cruise ship passengers had entered the river. We stopped along the way to eat some termites live out of the nest (they tasted surprisingly good!) and we walked a narrow, muddy path in the rainforest, with no sign of other humans anywhere in sight. All of a sudden, a call in the rainforest caught our attention: we'd found some howler monkeys. Charlie explained all about the howlers, and ensured that it was safe for us to venture off the path a few feet so we could clearly see the monkeys high up in the canopy.
Afterwards, we entered the caves and briefly jumped into the refreshing water for a quick swim, before getting in our tubes. Charlie guided us through the caves --and since we'd walked further than any other cruise ship passengers, we had the first two caves totally to ourselves-- all the while explaining all about Mayan traditions and beliefs. We asked Charlie if he could find us some bats in the cave, so he did...but if we hadn't asked we never would have seen any of them. The caves themselves are incredible, and we covered about two miles of them. When we finally arrived back where we'd started, we wished we could turn around and do it all over again.
At the end of the tour, we sat down to a satisfying meal of chicken, beans and rice, before getting back into the air conditioned van and driving back to the cruise terminal. All in all, a perfect tour, filled with experiences we never would have had if we had booked through the ship.