Secrets of the Underground
We checked 8 streaming services in India on 04 Jun 2026 at 08:16 IST
About
A search for an underground escape route said to have been used by Al Capone. Also: who or what built earthen mounds in Washington state.
Episodes
Season 1
Capone's Escape Tunnels
Rob Nelson investigates rumors of a secret underground escape route used by the infamous gangster Al Capone. In Washington state, Rob tries to uncover who -- or what -- built a vast landscape of earthen mounds in Washington state.
Mystery of the Serpent Mound
Rob Nelson explores mysterious tunnels beneath Denver's airport and capitol building to investigate rumors of a secret organization operating below. In Ohio, he tries to uncover the ancient secrets of a mound shaped like a serpent.
America's Buried Massacre
Rob Nelson hunts for a legendary mass grave that could expose a dark secret of America's industrial past. High in the mountains, a giant lake is mysteriously disappearing, and Rob uses cutting-edge technology to find out why.
Rocky Mountain Monsters
Rob Nelson examines a set of bizarre markings that suggest a violent clash between prehistoric beasts. In California, he investigates if a strange lake is a home to alien life.
Great Lakes Bermuda Triangle
Rob descends into a cave 30 feet beneath Texas in search of evidence of a mass extinction event. Then, he heads to Lake Michigan to investigate a Bermuda Triangle-like phenomenon that has caused ships to vanish for centuries.
California's Hidden Doomsday
Rob Nelson heads to California to investigate a network for major fault lines that could set off an unprecedented mega-quake. Then, he explores a mysterious sinkhole that some believe is an endless pit to the center of the Earth.
Secret History of the New World
Rob investigates ancient ruins in New England that suggest Europeans arrived in the Americas almost 1,000 years before Columbus. Then, he heads to California where a dormant super-volcano may be showing new signs of life.
American Stonehenge
Rob Nelson investigates the mysterious pattern of rocks at the bottom of Lake Michigan known as Underwater Stonehenge. At the notorious Alcatraz prison, Rob uses state-of-the-art technology in search of rumored escape tunnels.
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Watch Secrets of the Underground Online Free — All Episodes in HD
If you've been searching for Secrets of the Underground all episodes in HD, CineFlixo has you covered. This talked-about Inglés reality and documentary title from 2017 is available to stream instantly — no ads to fight through, no paid subscriptions, no annoying redirects.
About Secrets of the Underground
A search for an underground escape route said to have been used by Al Capone. Also: who or what built earthen mounds in Washington state. Across 2 seasons and 16 episodes, originally airing on Science.
Where to Watch Secrets of the Underground Online
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▶ Watch Secrets of the Underground NowWhy People Are Watching Secrets of the Underground
Secrets of the Underground flies under the radar but it deserves your attention. What makes it work is a tone and style that's hard to find elsewhere. If you enjoy Inglés storytelling that doesn't follow the same tired beats, this is the kind of show you'll end up recommending to friends.
Frequently Asked Questions about Secrets of the Underground
Where can I watch Secrets of the Underground online for free?
You can watch Secrets of the Underground online free on CineFlixo. Just open the page and hit play — no signup, no subscription, full HD streaming on phone, tablet, or desktop.
How many episodes does Secrets of the Underground have?
Secrets of the Underground has 16 episodes across 2 seasons. All episodes are available to stream right here on CineFlixo.
Is Secrets of the Underground good? What's the rating?
Secrets of the Underground holds a 5.5/10 rating based on 4 reviews — a niche pick worth checking out.
Is Secrets of the Underground available in Inglés?
Yes — Secrets of the Underground was originally produced in Inglés and that's the version you'll stream here on CineFlixo. English subtitles are provided when available.
When was Secrets of the Underground released?
Secrets of the Underground first aired in 2017.
Do I need an account to watch Secrets of the Underground on CineFlixo?
No. CineFlixo is free and you can watch Secrets of the Underground without creating an account. Sign-up is optional — only useful if you want a personal Watchlist or to comment on episodes.
Frequently Asked Questions
Where can I watch Secrets of the Underground for free?
You can watch Secrets of the Underground online for free on CineFlixo. All 16 episodes across 2 seasons are available to stream in HD without a subscription, signup, or paywall. Just open the show page and press play.
How many seasons and episodes does Secrets of the Underground have?
Secrets of the Underground currently has 2 seasons and a total of 16 episodes. The series status is "Ended", so the episode count may grow as new seasons are released. You can browse the full episode list on CineFlixo and continue watching from where you left off.
What is Secrets of the Underground about?
A search for an underground escape route said to have been used by Al Capone. Also: who or what built earthen mounds in Washington state. It belongs to the Reality, Documentary genres.
In which language is Secrets of the Underground originally available?
Secrets of the Underground was originally produced in English. On CineFlixo the show is available in its original English audio, which is the most authentic way to experience the dialogue, music, and performances. Check the player options on the watch page for available subtitle tracks.
When was Secrets of the Underground first released?
Secrets of the Underground first premiered on February 14, 2017 (2017). The series has since concluded its run.
All Seasons
Browse every season of Secrets of the Underground — 2 seasons in total
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