Though relatively small in area, Mexico has within its borders virtually every habitat that supports plant and animal life. From steamy jungles to cool cloud forests to arid deserts, it is one of the five most ecologically diverse countries in the world and hosts one tenth of all land species, including many which are found nowhere else. Needless to say, it also has a record number of species on the conservationist’s critically endangered lists.

     One of Mexico’s, indeed the planet’s, outstanding ecological treasures is the Pozos Azules (Blue Holes or Wells) in the Cuatro Ciénegas (Four Marshes) basin of Coahuila. This incredible basin is small, covering an area of only 30 by 40 kilometers, less than 350 square miles, yet it provides a number of unique aquatic and terrestrial habitats. These include tufa deposits, thermal and non-thermal springs, crystalline spring-fed streams, cenotes (sinkholes), lagoons and extensive marshes.

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