The Sian Ka'an Biosphere Reserve, 15 minutes south of Tulum or about two hours south of Cancun, is Mexico 's third largest protected area and a UNESCO – designated World Heritage site.

True to its name – in Mayan meaning “where the sky is born” – Sian Ka'an soft, pale blue waters melt into the sky at the horizon. Spanning more than 2,000 square miles between Tulum and Akumal, just north of Belize , the reserve boasts tropical forest, mangrove wetland, freshwater canals, lagoons, savannah prairie and 70 miles of the second longest barrier reef in the world, all rolled up into one dense “hot spot” of life.

Not surprisingly, the varied landscape is home to an abundance of birds and animals. More than 345 species of birds thrive here, including the rate Jabiru stork and more than a million wintering migratory song birds form the U.S. and Canada , which make wintertime tours ideal for bird-watching aficionados. All of the endangered cat species of southern Mexico are also found here, including the jaguar, puma and ocelot, though their nocturnal habits make sightings rare.

What's more, the remnants of some 27 Mayan sites, including one building which may have served as a customs check point for traders transporting goods via the canals, have been found on the reserve.