This Deadly but Beautiful Underwater River in Mexico Is an Adventure for Extreme Divers

Some of the most spectacular sights in the world are also the most dangerous. In Mexico, there's one such destination, a stunning underwater river that only a handful of people in the world have seen: an eerie pool of water in the sinkhole Cenote Angelita, which translates to "little angel."

According to a report from Science Alert, Cenote Angelita is located near the ancient city of Tulum on the east coast of the Yucatan Peninsula. Between the vast Caribbean Sea and the Gulf of Mexico, this cenote is a place where fresh water and salt water mix because when limestone collapses and sinks, the water from the sea meets the fresh water.

The area where the two mix - fresh water above and the salt water below - is called the halocline, which can be a shield and keep litter like leaves and other light trash from sinking lower. When a good amount of organic matter makes its way in the cenote, it can create a haze of hydrogen sulfide, which can kill any human who breathes it in.

The cloudy river of death is 30 meters (100 feet) from the surface. It's three meters thick, a colorless gas that smells faintly like rotten eggs.

Canadian videographer Mike Conley talked about the experience of going deep into the cenote's depths in a video on YouTube. He said, "Once through [the cloud], it turns into a night dive, and you need to use your torches. You only have a few minutes beyond the layer before you have to start ascending again. It's a murky landscape, with petrified trees sticking out of the cloud."

"Mayans believed that cenotes were the gateway to the underworld, and yeah, after visiting this one in particular, I can see why," Conley added.

Cenotes in Mexico formed thousands of years ago, according to a report from Mother Nature Network. The different pools of water in the country have been used for drinking water for centuries and are even at the heart of some Mayan religious ceremonies.