The Mesoamerican Reef is located along the Caribbean Riviera of Mexico. Although this area offers first class scuba diving in the world’s second largest barrier reef, this area is unique for another reason. The Yucatan Peninsula is home to the world’s largest underground water system.

Over thousands of years the peninsula's karst structure, composed almost entirely of limestone, has eroded away leaving large underground cave systems decorated with fragile and timeless calcite formations (stalactites and stalagmites). As cave ceiling walls collapse, cenotes are formed. These cenotes, from the Yucatan Mayan word "dzonot", is a type of freshwater-filled sinkhole. They lead into cave systems that cover the peninsula and lie just below the surface bedrock.

More than 500 years ago it supported an ancient civilization, the Maya. Today its winding passageways are windows into an underground waterway, a world to be explored.