Underground Worlds (2019)
- Genre: Documentary
- First Air Date: 2019-09-25
- Last Air Date: 2022-03-14
- Total Seasons: 2
- Total Episodes: 20
- Status: Returning Series
- Episode Runtime: 45 min.
- Production Country: United Kingdom
- Network: U&Yesterday
British documentary series exploring incredible feats of human endeavour underground, revealing what people have built, where they have built it, how and why.
| Title | Air Date | Duration | ||
|---|---|---|---|---|
| Season 1 | Episode 1 | Gibraltar | 2019-09-25 | 60 min |
| Season 1 | Episode 2 | Sweden | 2019-10-02 | 60 min |
| Season 1 | Episode 3 | Switzerland | 2019-10-09 | 60 min |
| Season 1 | Episode 4 | Kingdom of Salt | 2019-10-16 | 60 min |
| Season 1 | Episode 5 | Bouzincourt | 2019-10-23 | 60 min |
| Season 1 | Episode 6 | City of Naours | 2019-10-30 | 60 min |
| Season 1 | Episode 7 | Jersey War Tunnels | 2019-11-06 | 60 min |
| Season 1 | Episode 8 | The Maginot Line | 2019-11-13 | 60 min |
| Season 1 | Episode 9 | Edinburgh Vaults | 2019-11-19 | 60 min |
| Season 1 | Episode 10 | Dover War Rooms | 2019-11-27 | 60 min |
| Season 2 | Episode 1 | Hotel Bunker of the Apocalypse | 2022-01-10 | 60 min |
| Season 2 | Episode 2 | Grand Canyon's Lost Treasure | 2022-01-17 | 60 min |
| Season 2 | Episode 3 | Cincinnati's Secret Caverns | 2022-01-24 | 60 min |
| Season 2 | Episode 4 | Hotel Bunker of the Apocalypse | 2022-01-31 | 60 min |
| Season 2 | Episode 5 | Mystery of the Kentucky Cave | 2022-02-07 | 60 min |
| Season 2 | Episode 6 | Ireland's Underground Alcatraz | 2022-02-14 | 60 min |
| Season 2 | Episode 7 | Medieval Maze of Secrets | 2022-02-21 | 60 min |
| Season 2 | Episode 8 | Buried Lab of the Black Hills | 2022-02-28 | 60 min |
| Season 2 | Episode 9 | Subterranean Silo Survival | 2022-03-07 | 60 min |
| Season 2 | Episode 10 | Italy's Subterranean Secret | 2022-03-14 | 60 min |