Shame these wild-life programmes aren't backed up by proper science. For instance, they said that limestone is porous; also that limestone is soft (he's obviously never tripped up on a limestone pavement).
Then ? such and such a monkey 'was designed' for something or other; no, it evolved.
Some bird 'was designed' for catching bats; not, it evolved to catch bats.
'The gods are smiling (or some such rot) this year, as the rains have come'; OK, so it's tongue in cheek. But why do they kow-tow to superstitious nonsense?
'It's a remarkable fact that the water in the cenotes "flows"'; well it would, wouldn't it? Otherwise it would just rise up and flood the whole place. Although I accept that it's remarkable that it flows over what seem to be very long distances.
'Salt water is heavier than fresh water'; no, it's denser.
Perhaps the most remarkable fact about the underwater caverns was totally ignored ? that they are full of formations, which means that at one time they must have been above water.