This series, produced for the reader s digest, reveals the wonders that lie hidden below our feet. Episodes journey through subterranean worlds whose contents are surprising, dramatic, awe inspiring and even magical, invisible from above and often little known...until now.natural wonders join intrepid cave divers charting the beautiful mayan underworld hidden beneath the forest floor, scientists exploring an underground lake that has been sealed by ice for 4 million years, visit deep caves that are home to a million bats and others that provide life saving salts to herds of visiting elephants, caves that were excavated to create human settlements 18 storeys deep and most magically, the vast naiva caves in mexico which are full of sparkling, fairy tale crystal.but perhaps the most astonishing and mysterious sights of all are the cave paintings of attamira, profoundly moving artworks created in deep, inaccessible locations by humans who lived 90,000 years ago.