Sian Ka'an

Its Mayan name translates as 'origin of the sky', and Sian Ka'an lives up to it: a watery wilderness on the Caribbean flank of the Yucatán Peninsula where tropical forest dissolves into mangroves, marshes and a lagoon-laced coast guarded by a barrier reef. More than 300 bird species share the reserve with crocodiles, manatees and jaguars moving through its cenote-fed wetlands. UNESCO inscribed the biosphere reserve as natural World Heritage in 1987.