Five wonders at Son Doong Cave  The majestic scenery inside the Son Doong cave is beyond the imagination and creativity of artists.   Recognized as the largest natural cave in the world, Son Doong – in the central province of Quang Binh - contains many secrets that scientists cannot decode yet. This is a destination that Western tourists are willing to pay $3,000 for a tour, but they will have to wait until 2016 since the tours have been fully booked. Below are the five interesting facts about the cave. 1. Being discovered on a rainy day In 1991, Ho Khanh, a local man accidentally discovered Son Doong cave when he sought shelter from the rain. It wasn’t until 2009 when the explorers of the British Royal Cave Exploration Association came, Ho Khanh told them about the cave. Part of the cave roof collapsed a few centuries ago. As a result, rain water and sunlight can reach here, creating favorable conditions for plant development in the grotto. Photo: Huffington Post. Ho Khanh struggled to find the entrance which is located deep in the jungle with rugged terrain, far away from the main road and could not be seen with Google Earth. Thanks to his guidance, the British explorers went deep into the cave to take photographs, survey and collect scientific data. 2. Can accommodate a 40-storey building Son Doong has a width of 150m, over 200m tall, at least 5km long. The actual length of the cave may be even longer but the British explorers could not explore the entire length of the cave due to technical limitations. Still, with the recognized size, Son Doong has passed Deer in Gunung Mulu National Park in Malaysia (120m tall, 150m wide, 2km long) to become the largest natural cave in the world. Some sections inside the cave are up to 140mx140m, including 14m high stone columns. Photographer Carsten Peter took a photo of a cave section with a width of about 91.44m, a height of 243.84m, which means that it can accommodate a 40-storey building inside. 3. Formed five million years ago According to scientific documents, Son Doong cave was formed when river water flowed through the limestone buried along a fault line. After millions of years, water currents eroded and created a giant tunnel in the ground below the mountains. In the areas where rock was soft, the ceiling collapsed, creating holes which gradually became giant domes. 4. Rich fauna   Son Doong cave's ceiling collapsed centuries ago, creating a lush forest inside the cave, which was named by the British explorers as Eden forest. This forest is inhabited by monkeys and flying foxes. Many types of ferns, palms and vines cover from outside to the inside of the cave. The ancient lakes, waterfalls, rivers inside the grotto have formed rich algae and flora systems. In particular, the explorers also discovered a species of pearl which is formed from the process of dripping water, creating calcite crystals on the sand. 5. Why are visitors to Son Doong Cave restricted? Son Doong cave does not welcome many visitors because it must be protected for research. Currently, the mysterious world inside the cave has not been decoded completely. Therefore, Son Doong cave welcomes explorers and scientists rather than curious visitors. T. Van, VietNamNet Bridge