Cenote Angelita: An sinkhole beneath the ocean with a river underneath
We all know that Earth isn't flat in any way, all thanks to ancient Greek mathematician Pythagoras who first pointed out about its spherical shape. Anyhow, we humans love our home planet’s mesmerizing topography full of hills, valleys, mountains, caves, forests, deserts, and most importantly the expansive and mysterious marine world.
Do you know that our planet is also home to lakes and rivers under the sea? For instance, there’s something like an underwater sinkhole, better known as ‘cenote’. One of them, located in between the Caribbean Sea and the Gulf of Mexico is called Cenote Angelita (meaning “little angel”). This water-filled reservoir is found near Mexico’s Yucatan Peninsula and an underground river flows beneath it. Simply put, it’s an underwater world in itself.
Cenote: A sneak peek into this underwater sinkhole
A cenote is a naturally occurring underground water reservoir (identical to a sinkhole or a natural well) native to Central America that is formed when a limestone bed collapses exposing ground water underneath, like the one in Yucatan Peninsula. Cenotes receive their water from underground rivers originating in the Earth's core that is in turn filtered by rainwater and turn fresh. Maybe that’s why if you dive into a cenote, the water feels soothing.
A fascinating legend exists about cenotes among the Mayans (Mesoamerican Indians living in southern Mexico). They believe that the cenote is the entrance to the Xibalba (underworld), where the Mayan god Chaac (the God of rain, lightning, and thunder) resides. Ancient Mayans used cenotes for religious rituals or during human sacrifices. However, that's not it. Cenotes also happen to be the primary water source of the Mayans.
The hidden rider underneath Cenote Angelita
Now that you know what a cenote is, let’s move on the underwater river that flows beneath Cenote Angelita. An undersea photographer named Anatoly Beloschin discovered it while taking a dip in this cenote.
This underwater river flows 30 metres below the surface of the cenote and this is where salt water of the sea meets the fresh water of the cenote. Strange, isn’t it? But this isn’t the most startling fact about this under-the-ocean river.
Turns out, this river is covered by a thick cloud comprising of hydrogen sulfide (a toxic gas that smells like rotten eggs and is used in analytical chemistry experiments and various industries) which, if inhaled in large amounts, can be fatal to humans. Guess where this gas comes from? It is released by microbes (that thrive on the sea floor) when they breakdown organic waste. Okay, but other than being fatal, what else does this gas do in this river? It settles at the bottom to form a distinct layer. Why? Because its density is heavier than salty sea water which in turn separates the fresh water.
Just imagine oil and water in a vessel and you will be able to figure out how it looks. This thick layer of foul-smelling gas is found in the river's natural curves and bends. So, even though the cenote Angelita is a deep and tranquil underwater sinkhole safe for swimming, if someone goes 30 metres farther down, they will not only find a misty river full of toxic gas which may take his life too!
Mussels, the sole survivors of Cenote Angelita’s toxic river
The river underneath Cenote Angelita is nameless till date. In addition to the swamp gas (nickname of hydrogen sulfide), the river also consists of brine and methane. It is so toxic and dense that even a submarine cannot pass through it, while its depth makes it unfit for fishing. As a result, most of the usual aquatic flora and fauna cannot survive here. However, certain species of mussels can be seen along this underwater river banks! Unlike other marine animals, these sturdy creatures can thrive in methane and the toxic environment, even in the absence of sunlight! Bacteria that transform chemicals and methane into energy provide them with necessary nutrients for survival.