A video has surfaced of visitors to Costa Rica's infamous 'Cave of Death' with each marveling as the oxygen-deprived chamber snuffs out a giant torch in seconds.

The clip shows a tour guide waving a large torch with a foot-long flame into the mouth of the Central American cave.

In under seven seconds, the potent concentration of carbon dioxide gas (CO2) that pours out of the cave suddenly snuffs out his torch.

Further illustrating the unusual atmosphere within the 'Cave of Death' ('Cueva de la Muerte'), the weight of this heavier CO2 can be seen flattening the torch's plume of smoke as it wafts away, leaving a flat plane of eerie grey smoke.

The shape of the smoke, as it oozes out of the cave, is a sign of how this thick CO2 gas presses downward, squeezing oxygen out of the cave entrance.

'Small animals will enter the cave and asphyxiate, usually in a few moments,' Belgium-based cave explorer Guy van Rentergem explained.

The cave is continuously fed carbon CO2 from a nearby volcano, the Poas Volcano, which enters from the back of the geological formation. 

Every hour, as much as 66 pounds of CO2 flows out of the 'Cave of Death,' according to van Rentergem, who is also a trained chemical engineer.

'In a year, this is 263 tons of carbon dioxide or equivalent to a car driving 2.2 million kilometers [1.4 million miles],' van Rentergem said, 'or 56 times around the world.'

The only giveaway that this invisible CO2 flow poses any risk to living things at all is a warning sign adorned with ominous skulls and crossbones that exclaims: 'Danger! No trespassing beyond this point.' 

Fortunately, humans have generally been spared from the deadly cave, as it is too small for a person to fit into, although foraging snakes, birds, rodents and other creatures have met their end there.  

Costa Rica's 'Cave of Death,' found in the district of Venicia, could have this outcome too, for anyone who recklessly pokes their head inside its low-hanging entrance. 

The levels of CO2 gas flowing from inside the cave are so high that they can knock someone unconsciousness in an instant, quickly preventing them from breathing.

'This is a very small cave,' van Rentergem acknowledged, 'but it's unusual in that there is a substantial seep of carbon dioxide gas coming from the far slot at the back of the cave.'

Now a part of the Recreo Verde tourist complex, the Cave of Death measures roughly 6.5 feet deep and 10 feet long, and is safe to view standing a few feet away, however.

In fact, Michael Adrescon's recent video of the cave, which has been reported on Elon Musk's social media site X multiple times this month, was posted to TikTok with an encouragement to vacationers to go and check out this morbid attraction.

'Discover the exciting adventure of exploring the Cave of Death,' Adrescon's post reads. 'Immerse yourself in the natural beauty of this unique place!'

Some commenters beneath of the original Tik Tok post, however, had more scientific interest in the clip, treating it almost like a visual aid in a high school chemistry class.

'This is why the specific gravity of gasses is important,' TikToker @tehchanka pointed out. 'Carbon dioxide is heavier than air and will displace oxygen [at] lower levels.' 

'Methane is lighter and will displace oxygen at higher levels,' they added

More often called 'relative density' today, specific gravity is a ratio that compares any one type of gas to the density of ambient air at room temperature. 

Other commenters left their viewing experience mostly just terrified by the threat of an odorless, colorless and invisible concentration of CO2 that could render a tourist dead within minutes of poking around the wrong cave.

'That’s the most scary thing when sightseeing caves,' one TikToker said. 'You won’t even know when you faint.' 

There are other caves across the world with high levels of CO2 gas, including Movile Cave in Romania and Carburangeli Cave in Italy. 

Famously in the UK, Peak Cavern in Derbyshire was the location of a tragic accident involving British student Neil Moss in 1959. 

The 20-year-old Oxford University undergraduate lost consciousnesses due to CO2 inhalation, but there is some debate suggesting this was from his own exhaling of CO2, which built up in the base of the cave shaft.

A 2022 study by Italian researchers pointed out that natural caves are particularly prone to 'hazardous CO2 accumulations.' 

That's because they foster the release to the atmosphere of 'geogenic' CO2, meaning CO2 that comes from the Earth's natural geological processes. 

'Atmospheric CO2 concentrations can reach high levels inside natural caves,' the study authors said, 'representing a hazardous condition for humans frequenting the underground environment.'