I think the coolest part of the park was just the fact that most of it is underground, the whole time you are walking through caves full of stalactites and stalagmites which all by itself was fun. And of the above ground activities we were rarely with our feet on the ground because we were flying through the air on the zip lines.
The amphibious vehicles were more like all-terrain vehicles, we did go through some water but it didn't really submerge the cars, that being said, it was still an entertaining ride. When you could distance yourself from the car in front of you, you could get up some speed going around the turns and up and down the hills. We got to drive through the caves and across rope bridges too!
It seems kinda tame compared to the other activities but I liked the swimming through the underground river a lot. The water was a pretty blue, again there were stalactites and stalagmites everywhere, bats flying around overhead, and lots of swimming shenanigans with the friends. At the end of the swimming, we came out to an opening to ground level with water pouring in like a waterfall, it felt like a monsoon just started up outside, that part was awesome!
I'd highly recommend anyone visiting this area of the world to go to Xplor, if for nothing else just for the unique topology Mexico offers with its system of underground rivers; I'd have to say this is probably the best way you can experience them!