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Some of the world's most confounding archeological and architectural secrets are located close to home and just beneath our feet. With the recent emergence of cutting-edge technologies such as ground penetrating radar (GPR), LIDAR (Light Detection and Ranging), and 3-D imaging, scientists are now able to research fascinating underworlds of secret tunnel networks, ancient structures, and bizarre geological occurrences that offer glimpses into our history like we've never been able to see before. In the new Science Channel series, , premiering Tuesday, February 14 at 10 PM ET/PT, scientist and tech fanatic Rob Nelson travels the country to investigate long lost, subterranean phenomena. From intricate and forgotten sewers and caves, to lost civilizations and structures, SECRETS OF THE UNDERGROUND looks at all things covert, hidden and unfamiliar. The premiere episode finds Nelson in Louisville, Kentucky, where it's been thought that Al Capone used underground passageways as a secret escape route during Prohibition. And in Washington state, Nelson deploys a series of advanced scanning techniques to try to figure out the origins of thousands of earthen mounds that have baffled scientists for generations. Among the other mysteries that Nelson looks to uncover include the existence of a legendary network of complex tunnels at Alcatraz, long rumored by inmates to be a gateway to freedom; Lake Michigan's "Underwater Stonehenge"; and Pennsylvania's fabled mass grave.

How to Watch Secrets of the Underground Legally and Safely

If you want to stream Secrets of the Underground through reputable and legal services, there are a few good options depending on where you are. Subscription platforms like HBO Max, Disney+, Netflix, Amazon Prime Video, and Apple TV+ sometimes carry Secrets of the Underground films or related DC titles—though availability depends on your country.

If you’d rather not commit to a subscription, there are ad‑supported, free (but legal) platforms such as Tubi, Pluto TV, Peacock or Crackle (where available in your region) that occasionally host superhero films.

Lastly, don’t forget about library‑linked streaming options like Kanopy or Hoopla (if your library or university is registered), and official uploads by film distributors on YouTube—these can also give you legal access to classic movies.