Sian Ka’an: Sian Ka'an, word that in Mayan language means "gate of heaven" or "place where the sky begins', is a protected natural area and was declared" World Heritage" by UNESCO in 1987.
Its main characteristic is that its surface is mainly composed of limestone, which prevents the formation of superficial streams and favours the flowering of Cenotes. In front of the coast of Sian Ka'an, in the Caribbean Sea, there is a complex of coral reefs, the second most extensive of its kind, after the Great Barrier Reef on the east coast of Australia.
On the coast of this Reserve, there are white sandy beaches, small bays and mangroves, among other ecological systems.
A very peculiar ecosystem in the wetlands of Sian Ka'an is the “Petenes”, trees that can measure up to thirty meters high and rising among the marsh grasses. These plant formations are almost unique in the world, for out of the Yucatan peninsula, exist only in Florida, U.S.A, where they are known as hammocks, and in Cuba, where they are called “grove of trees”.
Reefs of Cozumel: It is considered as part of the barrier called "Great Reef Belt of the Western Atlantic" (also known as "Great Mayan Reef" and it belongs to the "Mesoamerican Reef"). It is a very important natural resource to the regional economy because in it activities of recreation, conservation, development, education, dissemination and monitoring are performed.
Probably the origin of the island corresponds to a detachment of the eastern side of the peninsula during the formation of the basin of Yucatan, between the Late Mesozoic and early Cenozoic. The limy soil of the island prevents the formation of superficial rivers, since all the rainwater seeps through cracks and fissures in the soil; so that runoff water do not carry suspended solids into the sea.
The submarine researcher Jacques Cousteau in 1960, show to the world the wealth of coral reefs surrounding the island, which made the enthusiasts divers realize the existence of Cozumel, in 1965, sparking the tourist development. On June 11th, 1980, it was federally decreed a "Zone of refuge for the protection of marine flora and fauna of the western coast of the island of Cozumel."