The Legends: The Giants' Fire and the Earth's Breath
For centuries, locals have spoken of the "Hot Hole" or the "Mouth of Hell" hidden in these mountains. Legends claim the cave is one of the Earth's "breathing vents," a place where ancient giants (Jidovii) were buried after a prehistoric war. The heat radiating from the depths is said to be their eternal inner fire.
Old folk tales warned that anyone entering without being "blessed" by the mountain spirits would be suffocated by smoke and the smell of brimstone. Another story suggests that Adam’s Cave was once a gateway to a subterranean empire, and the scorching heat was designed to keep intruders from discovering the secrets of the deep.

Shot of the entrance to Adam's Cave in the Cerna Mountains, Romania. The dark, circular limestone opening is surrounded by moss-covered rocks and green ferns. Light mist or steam is subtly visible rising from the depths, suggesting the thermal activity within. The ground is covered in natural debris and forest floor vegetation.
What makes Adam’s Cave legendary among scientists is its status as an active thermal cave. It possesses an extreme microclimate and an isolated ecosystem—a biological time capsule:
- The Heat: The air inside reaches incredible temperatures, up to 40°C (104°F), with humidity levels near 100%. This heat is generated by underground geological activity and massive biological decomposition.
- The Bat Colonies: The cave shelters one of the largest bat colonies in Europe, with millions of individuals from various species. These bats have created a massive layer of guano (bat droppings) that can reach depths of up to 4 meters.
- Thermophilic Beetles: Species of beetles and millipedes that exist nowhere else on Earth, perfectly adapted to the heat and total darkness.
- Rare Spiders and Worms: Entire food chains exist here, completely independent of the world above.
- Unique Microorganisms: Bacteria and fungi adapted to high temperatures play a crucial role in breaking down the guano, fueling this strange underground life.
Adam’s Cave is a strict speological reserve. Public access is forbidden and strictly controlled by the Romanian Academy.
- Toxic Gases: The decomposition of guano produces ammonia and other toxic gases which, combined with low oxygen levels, can be fatal.
- Suffocating Heat: The extreme temperature and humidity can cause rapid heat stroke and dehydration.
- Ecosystem Protection: The slightest human interference could destroy this fragile habitat. Even our breath can alter the delicate balance required for the bats and endemic species to survive.
FAQ (Frequently Asked Questions)
Q: Why is it called "Adam’s Cave"? A: The name likely comes from an early explorer or a local who first investigated it, or, according to some legends, from the shape of a gallery that supposedly resembles a human profile.
Q: Are there other thermal caves in Romania? A: Yes, but Adam’s Cave is unique because of its massive bat colony and high temperatures. Movile Cave (near Mangalia) (see more) is also a famous thermal cave, but it has a completely different ecosystem based on chemosynthesis.
Q: How can I help protect it? A: The best way is to support environmental and speological organizations in Romania that monitor and conserve these unique subterranean habitats.
Q: Do I need a permit to visit the "Forbidden Caves" or scientific reserves? A: Yes. Places like Adam’s Cave are strictly for scientific research. Access without a permit from the Romanian Academy or the local environmental authorities is prohibited to protect fragile ecosystems and for your own safety due to toxic gases and extreme heat.