The asteroid was a whopping 10-15 kilometres in diameter. Enormous. The impact altered the limestone rocks, weakening them and making them more susceptible to erosion.
Cenotes (freshwater sinkholes) are formed as naturally acidic rain filters down over thousands of years and dissolves away the (porous) limestone, creating hidden, underground, water-filled reservoirs. In the Yucatan, the caves are linked to other caves via numerous subterranean streams and rivers.
If geology is your thing (and even if it’s not), the sight of the resulting cenotes is amazing. They are not only stunning – the water is turquoise/jade green - but also very historically significant.
The word cenote comes from the Mayan word for water deposit or well and throughout the labyrinth, you may come across Mayan artefacts. Archaeologists believe that the Mayans saw these water passages as links to the underworld, as well as using them for water supplies and as a place to make sacrifices whilst communicating with their gods.