Movile Cave has been cut off for millions of years. Its air is thick with harmful gasses, yet it is home to an array of strange beings.

The cave remained unopened for 5.5 MILLION years. It was discovered in 1986 a few kilometers from the Black Sea coast after scientists were sweeping the area looking for the best spot to build a geothermal power plant. They never expected to find the most mysterious cave on Earth. The air inside the cave is very different from the outer atmosphere. The level of oxygen is only a third to half of the concentration found in open air, and it is home to a number of odd, weird-looking creatures.

Experts have discovered a total of 48-species in the enigmatic cave which remained sealed off from the rest of the world for 5.5 MILLION years.

Just imagine you stumbled across a cave that has remained sealed off from the world for 5.5 million years, what would you expect to find inside?

Basically, it’s a world inside a world, perfectly depicted in numerous Hollywood series and movies. However, there are times when fiction and nature are divided by an extremely thin line.

This is exactly what happened when experts explored the Movile cave—a chemical (chemosynthesis) world within the organic world of humans.

The cave is located in Southeastern Romania, close to the Black Sea. Located beneath the earth, this enigmatic ‘alien world’ has remained sealed off from the rest of the world for over 5.5 million years.

As explained by scientists, air inside the cave is very different from the outer atmosphere. The level of oxygen is only a third to half of the concentration found in open air (7–10% O 2 in the cave atmosphere, compared to 21% O 2 in air), and about one hundred times more carbon dioxide (2–3.5% CO 2 in the cave atmosphere, versus 0.03% CO 2 in air). It also contains 1–2% methane (CH 4 ) and both the air and waters of the cave contain high concentrations of hydrogen sulfide (H 2 S) and ammonia (NH 3 ).

The cave was found by Romanian scientist Cristian Lascu.

Accessing the cave is extremely hazardous. Visitors can only stay down for 5 or 6 hours before their kidneys pack in.

This mystery world can be accessed by descending an extremely narrow shaft, then climbing down through an ochre clay coated limestone tunnel which eventually gives access to a tunnel—filled with complete darknes—with a temperature of around 25 degrees celsius. The tunnel leads into a central cavern opening into a lake.

The ecosystem is beyond stunning.

Experts have discovered a total of 48 species including leeches, spiders, water scorpions and other insects, were found inside the cave, of which 33 are endemic. The food chain within the cave is solely based on chemosynthesis in the form of methane- and sulfur-oxidizing bacteria.

As explained by the BBC, in 2010, microbiologist Rich Boden, who was then at the University of Warwick in Coventry, UK, became roughly the 29th person to see the cave.

“It’s pretty warm, and very humid so it feels warmer than it is, and of course with a boiler suit and helmet on that doesn’t help,” says Boden, who is now at the University of Plymouth in the UK.

“The pool of warm, sulphidic water stinks of rotting eggs or burnt rubber when you disturb it as hydrogen sulfide is given off.”

**Article edited: Added images of some of the species that were discovered inside. Added a new video of the cave.

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