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Season 2 Episode
- Season 2 Murder Raid Tunnels
- Season 2 Grand Canyon's Lost Treasure
- Season 2 Cincinnati's Secret Caverns
- Season 2 Hotel Bunker of the Apocalypse
- Season 2 Mystery of the Kentucky Cave
- Season 2 Ireland's Underground Alcatraz
- Season 2 Medieval Maze of Secrets
- Season 2 Buried Lab of the Black Hills
- Season 2 Subterranean Silo Survival
- Season 2 Italy's Subterranean Secret
Underground Worlds - Season 2 Episode 5 Mystery of the Kentucky Cave
8.00 45 minutes Exploring the vast 400-mile Mammoth Cave in Kentucky, USA. Plus, a newly constructed opening into a metal mine in Wales - untouched for over 70 years.
