3D scans expose Britain's deepest mysteries in vast, hostile caves.
Descend with expert cavers into Britain’s flooded passages, towering shafts, and hidden chambers as cutting-edge laser scanning turns darkness into precise 3D worlds. Along the way, the series uncovers how caves form, what they reveal about ancient fears and human history, and why discoveries are still being made beneath familiar landscapes. Sign up to see exploration and science meet where few people ever go.
Episode guide
5 episodes- New shows weeklyFresh documentaries land every week.
- Exclusive originalsAward-winning films you can’t stream anywhere else.
- Watch anywherePhone, tablet, web and TV — pick up where you left off.
- No commitmentNo contract. Cancel in a click.
Frequently asked questions
Yes. Every plan unlocks the full library — including all Curiosity Originals like Underworld — in up to 4K, ad-free, on all your devices.
Underworld is a Curiosity Original, exclusive to Curiosity Stream.
Watch on the web, iOS and Android, Roku, Apple TV, Amazon Fire TV, Chromecast, Android TV, and most smart TVs. Start on one device and pick up right where you left off on another.
Curiosity Stream is our streaming service — thousands of documentaries and originals. The Smart Bundle is Curiosity Stream plus four other independent streaming services (Tastemade, Kidstream, Curiosity University, and SOMM TV) on a single subscription.