The outfit known as Major Tom and the Fun Team doing cave tubing in Belize were contacted by us at cave-tubing.net. Remarkably good operation - lots of experience apparently, from what we saw and enjoyed.
The canopy or zipline tour in Belize is next to the cave tubing site, making this combo tour of cave tubing/zipline very popular. The canopy tour has eight platform and is located in living rainforest, next to a limestone cliff that is part of the caves in which cave tubing is carried out. Pretty nice and easily arranged combination.