"Unlike other great civilisations 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 of extraterrestrial origin."