This 'cave of death' kills everything, including humans, that enters. The reason is...

Up to 30 kg of carbon dioxide are emitted per hour in Cueva De La Muerte. (Images: Recreoverde.com)

In the rugged volcanic terrain of Costa Rica’s Alajuela Province lies a sinister natural phenomenon: a seemingly innocuous crevice known as the Cueva De La Muerte, or the Cave of Death. Despite its modest dimensions—a mere six feet deep and ten feet long—this ominous site has earned a reputation for claiming lives with chilling efficiency. Unlike the typical hazards associated with wilderness, the peril here arises not from predatory beasts or venomous creatures, but from an invisible killer: toxic air.

Researchers have long warned of the lethal potential lurking in caves worldwide, but the conditions within the Cueva De La Muerte present a unique and deadly threat. Explorer Guy van Rentergem, captured in a 2022 YouTube video at the site, revealed the startling reality: “This is a very small cave, but it’s unusual in that there’s a substantial seep of carbon dioxide gas coming.”

Measurements show that up to 30 kg of carbon dioxide are emitted per hour—a silent menace that proves fatal to unsuspecting wildlife and even humans.

A solitary bird, its life snuffed out, serves as a haunting testament to the treacherous atmosphere within. Van Rentergem further explained, “The CO2 layer is essentially unreadable by small animals, or even humans for that matter. So small animals enter the cave and asphyxiate, usually within a few moments.”

What makes this cave particularly insidious is its deceptive appearance. Guides at the Recreo Verde Hotel and Spa, situated near the Poas Volcano, demonstrate the cave’s lethal capabilities by approaching it cautiously with fire torches.

The flames, a symbol of life and warmth, are swiftly extinguished by the suffocating carbon dioxide, leaving no doubt about the imminent danger lurking within. Here's a video of a demonstration filmed by Michael Con.

Costa Rica’s Cave of Death (Cueva de la Muerte) is a pool of carbon dioxide on the floor, which is remarkably stable, and nearly 100% CO₂: fatal to every animal that enters the cave.

See how a flame can't burn.

[ MichaelCon]pic.twitter.com/unb7j6Qo77

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— Massimo (@Rainmaker1973) April 11, 2024