Son Doong Cave the world’s largest, is located in Vietnam. It was originally found by a local man who discovered the entrance in 1991. He was afraid of the 300 foot drop and the roar that came from below. For 18 more years, it stayed unexplored until it was re-discovered in 2009 by British cave explorers. The name Son Doong means “mountain river”. The cave was created 2-5 million years ago by a river whose source is still unknown. The cave is so big it contains a jungle and you could fit a 40 story building inside.
Where the limestone was weak, the ceiling collapsed creating huge skylights. Thousands of “cave pearls” sit untouched in Son Doong. These were formed over hundreds of years when dripping water created layers of calcite that build up around grains of sand.
Vietnam has a very difficult terrain, and the cave is far out of the way. It’s totally covered in jungle, and you can’t locate anything on Google Earth. A team from the British Cave Research Association, who first explored Son Doong, will be returning to find out more of the cave’s mysteries.
A tour company called Oxalis, is running trial tours of the cave and accepting sign-ups for real six-day tours to take place next year. Ropes and harness are needed to get inside Son Doong, and any visitors will need to rappel 260 feet to reach the cave floor. Tourists will explore the cavern by day and sleep on the cave’s sandy beaches at night.
Ruminating 
I soooooooo want to go to Vietnam…not sure I will go so far out of the way, I’ve never caved before (so to speak) but these pictures are gorgeous…thanks for sharing!
I once went inside an underground tunnel in Vietnam. Used as hiding place for Vietnamese soldiers. The passage was so small but had since been enlarged for the tourists. There was a hospital and a kitchen inside however small and on top a burnt tanker. The jungle above it was full of traps, still there, but now harmless.
Astonishing nature.The cave is a breathtaking view.Thank you for visiting my blog.Best regards.jalal