Recreo Verde Tourist Complex in Venecia de San Carlos, Costa Rica, is home to a small cave in the mountains known as the Cave of Death due to its deadly potential for any creature that ventures inside.
Located at the edge of the Poás Volcano, la Cueva de la Muerte (Cave of Death in Spanish) is a small cave, only 2 meters deep and 3 meters long, seemingly providing a cozy refuge for insects, birds, and small animals seeking shelter.
However, unlike its innocuous appearance, entering this tiny cave can result in almost immediate death because it is filled with toxic gas, a colorless, odorless, tasteless, and extremely harmful gas. To demonstrate just how dangerous the Cave of Death is, local guides place a burning torch inside the cave, and it is extinguished instantly due to the lack of oxygen and high carbon dioxide concentration inside.
The Cave of Death is one of the most dangerous caves in Costa Rica. Hidden in the rainforest of this country, this cave has earned its deadly reputation as any creature that enters may never return.
No one truly knows exactly where the carbon dioxide in the Cave of Death originates, but some researchers have concluded that this phenomenon results from gas leaks appearing on the surface through fissures in the Earth’s crust known as the San Miguel Fault. The cave’s proximity to an active volcano may also contribute to the gas emissions.
Carbon dioxide is organically sourced, formed from mineral deposits deep underground, enduring high temperatures and pressure in the Earth’s magma, where there is no oxygen. It is also a byproduct of environmental pollution due to excessive fossil fuel use. It is characterized by its long-lasting presence in the environment—such as in the atmosphere—creating a greenhouse effect.
In the case of the Cave of Death, this gas is colorless and odorless. Additionally, it is dense and heavier than air, so when it accumulates in the cavity, it displaces and occupies the lower space of the cave.
One thing is for certain; scientists have discovered that the Cave of Death produces approximately 30 kilograms of carbon dioxide per hour.
Despite being a site of frightening phenomena, the Cave of Death has become a tourist attraction. The area has been developed with a range of hotels and accommodations in San Carlos. To ensure safety, the cave is surrounded by fences and multilingual warning signs. Tour guides often carry a torch, using it to illustrate the boundary between life and death as they lead tourists close to the cave. The flame will extinguish immediately when it comes into contact with the dense CO2 layer near the ground inside the cave.
The deadly characteristics of this small cave were discovered accidentally during the construction of the Recreo Verde complex. A worker who approached the entrance too closely began to feel fatigued, prompting a thorough investigation of the surrounding environment. Its deadly reputation has made the Cave of Death one of the few commercial caves that tourists cannot enter.
Inhaling high concentrations of CO2 can lead to CO2 poisoning. Symptoms include headaches, dizziness, nausea, vomiting, shortness of breath, and loss of consciousness. In severe cases, CO2 poisoning can result in death. CO2 can irritate the respiratory system, leading to difficulty breathing, coughing, and asthma. It can also reduce lung function, making breathing more difficult, especially for individuals with asthma or chronic obstructive pulmonary disease (COPD).
The Cave of Death has several warning signs advising people not to enter if they value their lives, but its small size and narrow entrance make it very difficult for individuals to access. Additionally, the dense carbon dioxide (with a purity of about 80-90%) typically resides at the bottom of the cave, making it even more dangerous for small animals. They will start to suffocate immediately upon entering the cave.
Long-term exposure to CO2 can increase the risk of cardiovascular diseases, including heart attacks and strokes. Severe CO2 exposure may lead to brain damage; it can affect the nervous system, resulting in issues such as anxiety, depression, cognitive disorders, and even death.
Similarly, another horrifying cave has been discovered in Saudi Arabia (the Umm Jirsan Cave), where a mountain of bones was found within a vast network of underground tunnels.
According to Live Science, this lava tube cave has been home to hyenas for thousands of years. These creatures are believed to have created the mountain of bones over a period of seven thousand years.
CO2 is the primary greenhouse gas responsible for climate change. Climate change is causing numerous negative impacts on humans and the environment, including rising sea levels, more extreme weather events, and loss of biodiversity.
When CO2 dissolves in the oceans, it increases ocean acidity. Ocean acidification is harming marine life, such as corals and fish.
