Beware of the 'Cave of Death': Terrifying cavern appears harmless to the naked ... trends now

From the entrance, it looks almost like a normal cave, with a rocky overhang and leaves scattered around the entrance. 

The only giveaway is a warning sign adorned with deathly skulls and crossbones saying: 'Danger! No trespassing beyond this point.' 

This is Costa Rica's Cave of Death – or 'Cueva de la Muerte' in the local Spanish – located at the Recreo Verde tourist complex in the district of Venecia. 

Measuring 6.5 feet deep and nearly 10 feet long (2 meters by 3 meters), it instantly kills any creature that enters it.

However, this isn't deterring brave explorers from making the visit to the site in the hunt for social media videos. 

Read More

Inside 'world's deadliest cave' that could cause next pandemic: Kitum in Kenya gave rise to Ebola and 'eye bleeding' Marburg virus

According to Belgium-based cave explorer Guy van Rentergem, who visited the site several years ago, it contains a substantial amount of carbon dioxide (CO2). 

In fact, levels of the gas inside the cave are so high that it can cause unconsciousness almost instantaneously, followed by cessation of breathing. 

Luckily, humans are generally safe because it's too small to fit into – and signs on the site provide a sufficient warning. 

However, snakes, birds, rodents and other small creatures quickly die after unwittingly wandering into the entrance, perhaps in search of food. 

'This is a very small cave, 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,' van Rentergem said. 

" class="c6" scrolling="no"