Over (pictured), one of the caves inside the Phong Nha – Ke Bang National Park.
During the rainy season, which runs from September to February, these cascading pools fill with water.
As water percolates through the limestone strata, it dissolves and carries minerals, particularly calcium carbonate.
When this water flows into the cave, chemical changes cause the minerals to precipitate, forming natural stone rims that gradually create the pools.
The cave was discovered in 1997 by an expedition team from the British Cave Research Association.
It measures 3.2 kilometers in length, with an entrance roughly 30 meters wide and 25 meters high.
Inside, the cave has a maximum height of 103 meters and width of 125 meters.