Riviera Maya Vacation - Joe McClintock
The cenote is a collapsed cave that has formed as a result erosion of the limestone.  Some of the cenotes are connected to the ocean by a labyrinth of underground caves or rivers.  You can see ground water cascading into the cenote.  In some of the cenotes the water turnover is quite rapid.

The cenote is a collapsed cave that has formed as a result erosion of the limestone. Some of the cenotes are connected to the ocean by a labyrinth of underground caves or rivers. You can see ground water cascading into the cenote. In some of the cenotes the water turnover is quite rapid.