Located in the Quang Binh province in Vietnam, the Son Doong Cave is the world's largest cave. The biggest section of the cave is more than 650 feet wide, almost 500 feet high, and approximately 5.5 miles long. According to the website, parts of the space are so massive that there are caverns big enough to fit an entire city street inside them.
Set along the Laos border, this largest single passage is part of a network of 150 other caves. It is located in a very remote jungle area within Phong Nha-Kẻ Bàng National Park and was rediscovered in 2009 by a group of British cavers.
"Son Doong" means "mountain river," and is aptly called such because the formation was created millions of years ago when river water eroded the limestone underneath the mountain. There is still much to discover, but so far, inside, explorers have found a fast-flowing river, giant stalagmites standing more than 230 feet high, and a tiny jungle, nicknamed "Garden of Edam."
On a side note, the Son Doong Cave is just one of the ten places we chose in the list Extraordinary Travel Destinations Off the Beaten Path. Make sure to check out the rest.