This tour was truly wonderful. Our guides were fantastic and the trip itself was well worth it. I learned a lot about Belize (history, local flora and fauna, food, etc). The tubing trip itself out to the river is around an hour in the van. You hike around a mile (river current dependent) and then take a lazy but beautiful tube trip down the river. The rock formations are just gorgeous. The tour group provides helmets, life jackets, and tubes. They had them ready for us at the trailhead too, which was nice for us in particular since we were tubing with our 5-year-old.
A few tips - Water shoes are a must for this trip! The hike to the head of the river can be sharp/rocky, as can the river itself. A good sole is important. Bring a lunch - there isn't much food at the base camp. By the time we were done with our trip, we only had tamales as an option and, while I thought they were tasty, I was the only one in my family that would eat them.
A suggestion to the tour group - It wasn't very clear what time we needed to be ashore for the tour. We were up super early to get one of the first tenders from out ship to shore only to have to wait for well over an hour for the rest of the group to arrive. It would be helpful to know if the tour departs on ship or local time and when to be ashore.