One of natural wonders in Vietnam and how to protect and preserve is Son Doong cave.The Son Doong Cave was formed about 2-5 million years ago, when river water flowing through the limestone mountains was buried along a fault line, creating a huge underground tunnel under the mountains. In the soft rocky areas, the ceiling collapses, forming holes, which are long, into giant caverns. The cave is 9km long, 200m wide, 250m high, 200m high and 2 entrances. Going deep into the cave, visitors will see countless stalactites, especially stalactites to 70 meters. In particular, at a place called adventurers called the Garden of Eden, visitors will encounter a magnificent rainforest, full of light blue with thousands of trees and plants such as birds snake, squirrel, monkey. An underground river flows through the basement about 2.5 km long. The flow of the river has brought shells, which accumulate in the river bed. Not far from the garden, there is a huge collection of "pearls" including tens of thousands of round, small rocks between the rocks in the shallow ponds. In the rainy season, the crystals of calcium in the water envelops small grains of sand to form huge "pearls", adorning the spectacular beauty of the cave.