From ice caves to secret underground military bunkers, watch as we take you through the most wondrous and incredible underground marvels of Season 1! The Great Altar - 00:00 - 07:30 Pionen Data Center - 07:30 - 15:24 Black Hole Trail - 15:24 - 22:57 Kingdom of Salt - 22:57 - 32:00 Caves of France - 32:00 - 38:04 Ice Caves - 38:04 - 45:53 Jersey War Tunnels - 45:53 - 52:34 Theodosius Cistern - 52:34 - 1:02:10