At first, the thought–let alone existence–of an underwater river seems paradoxical, if not impossible. Yet an underwater river is precisely what a group of amateur cave explorers discovered when they went scuba diving in Cenote Angelita (meaning “Little Angel”). A cenote is a natural sinkhole that forms when there is a collapse of limestone bedrock that exposes the groundwater below. These natural pits are generally connected to subterranean water sources and may contain deep underground cave systems.
Surprisingly enough, much of the underwater river looks and functions like a normal river. For instance, one can see the shore, marred by leaves, branches and silt, punctuated by a roiling stream. It’s only when the photographer steps back and you see a diver poised above the currents that you can wrap your head around this incredible natural occurrence. Those who have visited Cenote Angelita say it’s one of the world’s most surreal places.
Still can’t wrap your head around the concept of an underwater river? You’ll (almost) feel like you were there after watching this video:
An underwater river occurs when waters with different densities form layers (think back to third-grade science experiments when teachers combined oil and water for a similar effect). While the first 29 meters of Cenote Angelita are fresh water, the underwater river below is formed from a layer of water and hydrogen sulfide, which is significantly heavier. A halocline—a quick change in salt concentration that occurs within a slight depth—forms at the point between the two layers of water, creating a cloudy phenomenon that resembles fog.
For more out-of-this-world landscapes, explore the most surreal places around the globe.