Amazing Underground Secrets
Mastering the Underground World (#103)
Series Description: AMAZING UNDERGROUND SECRETS is an eye-catching, three-part series exploring the wonders that lie hidden below the planet's surface. It's a world of surprising, dramatic, awe-inspiring and sometimes magical things, from underground telescopes to crystal caves, from meandering tunnels to massive caverns to whole cities. Getting there is only part of the challenge; returning safely is a feat in itself.
Natural Wonders (#101)
Intrepid underground explorers make amazing discoveries and share sights of remarkable beauty. [56 minutes]
Secrets & Treasures (#102)
From ancient history right up to the present day, the underground world is the first choice for those seeking concealment. [55 minutes]
Some of the greatest human minds have been engaged in making the underground safe and accessible. Explore the most breathtaking feats of technology, past and present. [54 minutes]