S2 E6 ∙ Ireland's Underground Alcatraz ∙
Exploring hidden defences that have kept Cork Harbour, in Ireland, safe for over 400 years. Plus, a former submarine base in the fjords of northern Norway.
All episodes for series 2 of Underground Worlds
S2 E1 · Murder Raid Tunnels
Exploring the extensive air raid tunnels hidden beneath Ramsgate.
S2 E2 · Grand Canyon's Lost Treasure
Exploring inside the Grand Canyon Caverns - North America's largest dry cave system.
S2 E3 · Cincinnati's Secret Caverns
Exploring the forgotten underworld hiding beneath the streets of Cincinnati, USA.
S2 E4 · Hotel Bunker of the Apocalypse
Exploring the secret, Cold War US government bunker hidden under Greenbrier Hotel in West Virginia.
S2 E5 · Mystery of the Kentucky Cave
Exploring the vast 400-mile Mammoth Cave in Kentucky, USA.
S2 E6 · Ireland's Underground Alcatraz
Exploring hidden defences that have kept Cork Harbour, in Ireland, safe for many years.
S2 E7 · Medieval Maze of Secrets
Exploring tunnels beneath Exeter that were built in medieval times to protect the city.
S2 E8 · Buried Lab of the Black Hills
Exploring a former gold mine turned scientific laboratory in South Dakota.
S2 E9 · Subterranean Silo Survival
Exploring old tunnels in an abandoned tin mine beneath the moors of Cornwall.
S2 E10 · Italy's Subterranean Secret
Exploring the caves beneath the beautiful city of Orvieto in Italy.
