<!– google_ad_section_start –>
A new subterranean realm is discovered deep in the caves of Vietnam, in this clip from Season 18, “Secrets of Inner Earth.”
Watch all new episodes of Ancient Aliens, Fridays at 8/7c, and next day on The HISTORY Channel website at http://history.com/schedule.
Subscribe for more from Ancient Aliens and other great The HISTORY Channel shows:
Find out more about the show and watch full episodes on our site:
Check out exclusive The HISTORY Channel content:
History Newsletter – https://histv.co/newsletter
Website – https://histv.co/History
Facebook – https://histv.co/Facebook
Twitter – https://histv.co/Twitter
“Ancient Aliens” explores the controversial theory that extraterrestrials have visited Earth for millions of years.
The HISTORY® Channel, a division of A+E Networks, is the premier destination for historical storytelling. From best-in-class documentary events, to a signature slate of industry leading nonfiction series and premium fact-based scripted programming, The HISTORY® Channel serves as the most trustworthy source of informational entertainment in media. The HISTORY® channel has been named the #1 U.S. TV network in buzz for seven consecutive years by YouGov BrandIndex, and a top favorite TV network by Beta Research Corporation. For a deeper dive, visit history.com or follow @history on Instagram, Twitter, Facebook, YouTube and TikTok. For additional press materials visit the A+E Networks Press Center at http://press.aenetworks.com.
<!– google_ad_section_end –>