自然世界：玛雅地下世界之谜

　　Unlike other great civilizations such as the Romans and the Ancient Egyptians, the Mayan empire did not arise from the banks of a mighty river.
　　Much of the Mayan world is in fact devoid of even the smallest river or lake. Then why did they populate Yucatan? The Maya believed that the freshwater pools, ‘cenotes’, dotted across the area were sacred portals to the underworld.

　　They are indeed portals, but rather to an incredible underground labyrinthine systems of rivers. Only now being properly explored and understood, this secret world was created by nature in a unique chain of dramatic events.
　　Underneath the jungle-clad Mayan temples of Yucatan lies a world even more mysterious, even more incredible than the Maya could have ever imagined.
　　A whole food chain has been found in the cenotes deepest recesses — over 20 species that have never seen the light of day. Some of the underground caverns are not totally full of water… incredibly, they are home to thousands of bats.