A group of amateur cave explorers discovered a river in Mexico with banks, trees and leaves just like an ordinary river, but with an additional metric shit ton of “WTF,” because they were hovering 25 feet over it in scuba gear when they discovered it.

While underwater water doesn’t seem possible, the “river” is actually a briny mix of salt water and hydrogen sulfide. It’s much more dense than regular salt water, so it sinks to the bottom and forms a distinct separation that acts and flows like a river.

Deep sea lakes look like normal lakes, complete with sandy and rocky shores. Scientist call these lakes “cold seeps,” but they’re a hotbed for life, because apparently waterfront real estate is a hot commodity under water, too. The “rocky” shores are actually made up of hundreds of thousands of mussels. Even weirder, the lakes under the waves have waves of their own.

Photos by Anatoly Beloshchin, source,