In Yucatan there are approximately 8,000 cenotes.
They are the only source of fresh water in that Mexican state.
But they are much more than a resource: they have enormous cultural and even religious value for the community, Yamili Salazar, director of the civil organization Bacab, tells CNN en Español.
This organization works with more than 150 volunteers to promote environmental education in the region, and it does so by training children and youth so that they can monitor the water quality of the cenotes.
See here how his work is.