If you are an expert diver you should visit Cenote Angelita Cave in Mexico. Your dive towards the floor of the water-filled cave is amazing to say the least. As you get deeper the water turns from pure to salty; and the bottom, it’s a river. Deeper than 30 meters the water is pure, and deeper than 60 meters it becomes saline.
Some meters away before you get to the bottom of the cave, you see a river underneath, with trees and leaves floating on some liquid level. However it may seem like a river, it’s not a real river. It’s just a layer of hydrogen sulphide beneath. All in all, it looks startling and unforgettable when you get there and see it with your own eyes.
via : CrystalKiss