The largest cave in the world is located in Vietnam in Phong Na Ke Bang National Park.
It was accidentally discovered by a local farmer in 1991. But it was revealed by a British team in 2009.
It is five kilometers long, 200 meters high and 150 meters wide. An underground river runs through it.
There are 70 meter tall stalagmites which are the largest in the world.
Pearls the size of tennis balls were found there.
[Source: el.wikipedia.org]
