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© Patrick Landmann - photographs used with the express permission of the author

Movile Cave (Romanian: Peștera Movile) is a cave near MangaliaConstanța County, South-Eastern Romania, a few kilometers from the Black Sea coast. It was discovered by Cristian Lascu in 1986 at the bottom of an artificial shaft dug for geological investigations. It is notable for its unique groundwater ecosystem rich in hydrogen sulfide, methane and ammonia but very poor in oxygen. Speleogenesis in this area was initiated in the late Miocene (5.5 million years ago) and continues today by the action of the sulfuric acid resulted from the oxidation of sulfide in the lower part of the cave. Movile Cave was the first ever discovered subterranean chemosysthesis-based ecosystem.

Movile Cave is a 240 m long horizontal maze that has no natural entrance, having been sealed off from the surface during the Quaternary (2.5 million years ago) by thick and impermeable layers of clays and loess. The air in the cave differs significantly from the outer atmosphere in that the level of oxygen in the lower part of the cave and in the air-bells is only

7–16% O2 as opposed to 21% at the surface; there is a level of 1.5–3.5% CO2 in the cave, versus 0.03% in air. It also contains

1–2% methane (CH4) and both the air and waters of the cave contain high concentrations of hydrogen sulfide (H2S) and ammonia (NH₄⁺). Temperature inside the cave is 21°C

and relative humidity is approximately 100% with no detectable air movement.


The Movile Cave groundwater ecosystem is abundant and diverse. More than 50 species of cave adapted invertebrates, among them leeches, spiders and water scorpions have been found inside the cave, of which 37 are endemic (are found nowhere else). They evolved separately from the outside world since the cave was sealed off during the Quaternary. The subterranean food web is based on chemosynthesis performed in situ by methane- and sulfur-oxidizing bacteria, as well as nitrifying microorganisms. These form microbial mats that cover the water and the cave walls adjacent to the water. Large numbers of aquatic and terrestrial invertebrates graze on the rich microbial mats present in the lower sections of the cave, while others predate on protozoa and smaller invertebrates.

A full list of species found in Movile Cave

can be accessed by clicking here

Research has been ongoing in Movile Cave since its discovery in 1986. Today, researchers still discover new species unique to this ecosystem.  The cave is only accessed through an 18 m deep shaft that is closed off from the outside atmosphere by an air-tight gate.  This has ensured that the underground environment has remained undisturbed since its discovery.  While we encourage visiting scientists to apply for permission to conduct research, the access into the cave is drastically limited to only a few entries a year in order to minimize the visitors’ impact and to preserve the integrity of the cave environment.

A comprehensive list of scientific research papers and articles published by our scholars about Movile

and its ecosystem can be found on the Publications page.

To view some of the documentaries made about Movile Cave click here

For scheduling of research related projects please contact us for available dates and for additional information.

Schematic representation of microbial carbon, nitrogen and sulfur cycling in Movile Cave © adapted from Kumaresan et al (2014) Geomicrobiology Journal

Weird Places: Movile Cave

SciShow - 2016

Movile Documentaries

The Cave That Time Forgot

BBC - "Seeing Through Science" Series - 1994

The Secret Underworld

National Geographic Adventures - 1997

Movile Cave

Histories from the Black Sea - 2014

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