If you do love diving and do a diver, it is a good idea to visit the Cenote Angelita, Mexico. There is underwater river. Underwater rivers can be found in a cave if dive up to 30 meters depth, the water is freshwater, but if you dive to the depth of more than 60 meters, the water becomes salt water. In essence there is a "river" complete with trees and foliage. But, of course it was not unusual because the river is a river of hydrogen sulfide layer that looks like a river. Hydrogen sulfide, H2S, is a colorless gas, toxic, flammable, and smells like rotten eggs. These gases can arise from biological activity when bacteria break down organic material in a state without oxygen (anaerobic activity), such as in the swamp, the sea and sewage. Gas was also featured on the gas arising from volcanic activity and natural gas.
As in the picture, the sensation that we can we get the unique natural phenomenon where the sea looked like a river like a river that is on the ground. Perhaps, this unique phenomenon can be used with one of the seven wonders of the world.