[Our man in washington]

A question for you or anyone:

Did the impact from 65 million years ago create the conditions for these underwater caves and rivers?

[Owl558]

"Did the impact from 65 million years ago create the conditions for these underwater caves and rivers?"

That's a great question that I don't know the answer to. From my reading it is clear that the underwater caves were above the water-table at some point.

[null and void]

Did the impact from 65 million years ago create the conditions for these underwater caves and rivers?

YES! If you look at a map of the sacred cenotes, they form an arc centered on Chixulub:

More details Radar topography reveals the 180 km (110 mi) ring of the crater; clustered around the crater's trough are numerous sinkholes, suggesting a prehistoric oceanic basin in the depression left by the impact (Image courtesy NASA/JPL-Caltech).

[Bernard Marx]

Did the impact from 65 million years ago create the conditions for these underwater caves and rivers?

I don't see any relationship. The underlying rock in this area is limestone and the numerous caves in he region are caused by slightly acidic water. The limestone is soluble in acid and over time it's eaten away creating enormous caves, sinkholes and underground river systems. It's called Karst topography. Most of the world's large cave systems have been created by the same process.