On our boat trip, we saw wildlife, shrines, and some impressive geologic features. There were hundreds of black vultures gathering along the river.
There were also crocodiles sunbathing on the banks.
The river also has a serious problem with pollution. Along the river there were large deposits of garbage in the eddies and bends. Garbage and sewage builds up in this canyon since Tuxtla Gutierrez and other cities are just upstream. To say the least, I wouldn't go swimming here.
One of the main attractions along the canyon is the Arbol de Navidad (Christmas tree). This is a beautiful geologic feature that formed from deposits by running water. These fans of accumulated and became covered by moss and other plants, giving it the look of a tree.
At the end of the boat tour, you arrive at a large reservoir. From there, you turn around and head back up the river to the starting point.
We also took the driving tour along the top of the canyon. We were staying with a very nice family in Tuxtla Gutierrez, and they offered to go on a Sunday drive with us. We stopped in several locations along the canyon to take photos. We had a blast with our host, his sister, and his little five year old nephew.