

Underground Marvels
Season 2
TV-PG
British documentary series exploring incredible feats of human endeavour underground, revealing what people have built, where they have built it, how and why.
Where to Watch Season 2
10 Episodes
- Hotel Bunker of the ApocalypseE1
Hotel Bunker of the ApocalypseThe top-secret construction of a massive nuclear bunker remained concealed under a palatial West Virginia hotel for decades, and now, experts reveal how this vast subterranean structure was one of the most closely guarded Cold War secrets in US history. - Mystery of the Kentucky CaveE2
Mystery of the Kentucky CaveThe longest known cave system in the world spans hundreds of miles beneath the hills of Kentucky, and containing prehistoric artifacts and ancient human remains, experts reveal a subterranean mystery that may have changed the course of U.S. history. - Cincinnati's Secret CavernsE3
Cincinnati's Secret CavernsDeep beneath the streets of Cincinnati lies a network of deserted tunnels and caverns that contain a remarkable history of the city's origins, and now, experts investigate to reveal who built this underground labyrinth and why it was abandoned. - Buried Lab of the Black HillsE4
Buried Lab of the Black HillsBuried nearly a mile beneath the Black Hills of South Dakota is a cutting-edge laboratory at the forefront of astonishing scientific research; experts reveal advancements engineers achieved more than a century ago that keep it operating today. - Ireland's Underground AlcatrazE5
Ireland's Underground AlcatrazSubterranean military fortresses situated on the southern coast of Ireland have protected against enemy invasion for over 400 years, and now, experts investigate how this powerful stronghold transformed into a brutal and terrifying prison. - Grand Canyon's Lost TreasureE8
Grand Canyon's Lost TreasureDescending more than 200 feet beneath the Arizona bedrock lies the largest dry cave system in North America; experts explore this vast subterranean network to reveal the mysteries and undiscovered treasure that remain hidden within its walls.