A cave so big, that it actually has its own jungle, waterfall and river

It's strange that nobody even knew the cave existed until 1991 when it was discovered for the first time by a local native named Ho Khanh, who didn't even dare to go in because the entrance was too steep. It was rediscovered to the world by a group of British explorers (cavers) in 2009. When setting foot in the 8.8 km (5.5 miles) cave the Brits first came upon a giant chamber 4.8 km long, 198 meters high and 150 wide - dimensions that already transcend all previous discoveries. The cave is so big that it actually has its own river, waterfalls and a jungle.

Just for the record, the longest cave in the world is the Mammoth Cave in Kentucky (400 miles of passageways) and deepest Krubera Cave (2.197 meters/ 7.208 ft) in the nation of Georgia.

The name Soo Doong means "mountain river cave". The cave was created 2-5 million years ago by a the river waters that slowly eroded the week limestone under the mountain.

Organized tours first started last year after a tour company Oxalis did some trial tours of the cave. This year only 224 people will have the privilege to explore the cave.

The 3 night adventure begins with a 80 meters drop into the cave and after a day of exploring the visitors will camp near a place called Hand of Dog (a giant stalagmite that looks like a dog`s paw).

The next day they will visit another interesting site named the Garden of Edam, a place where the roof of the cave collapsed and allowed the vegetation to take root. Son Doong is also famous for its rare cave pearls formed hundreds of years ago. Scientist have also discovers unknown plant species around the waterfalls of the cave and fields of algae formed from ancient pools.