World's Largest Cave

Hang son Doong cave  is a cave in Phong Nha-Kẻ Bàng National Park, Vietnam. Currently the biggest known cave in the world, the cave is located near the Laos-Vietnam border (17°27'25.88"N 106°17'15.36"E). Inside is a large, fast-flowing underground river.

The cave passage in Phong Nha-Ke Bang National Park was originally thought to be a modest 150 metres long and 200 feet high.At  a mammoth 2.5 miles long, 330ft wide and almost 800ft high, Hang Son Doong - also known as Mountain River Cave - is as high as 25 double decked buses.

In 2009, a group of scientists from the British Cave Research Association began an extensive survey of the cave's depths.The jungle found inside of the cave has formed underneath a collapsed roof in one of the caverns. After the roof collapsed, enough light spilled into the cavern that vegetation was able to creep in slowly from outside. As the vegetation took hold, larger and larger plants began to grow, and now hornbills, flying foxes, and monkeys dwell in its branches. 

 In 2013, public visits started to be offered by Oxalis that offer the chance to spend days inside exploring, as well as camping, in this massive cave. .