Mammoth Heritage Cave found in Vietnam

The cave in the Annamite Mountains contains a river and jungle (its name translates to "mountain river cave") and even its own thin clouds, and its end remains out of sight. It's part of a network of about 150 caves in central Vietnam near the Thai–Laotian Border.

An excerpt from the article of National Geographic reveals more about the massive cavern:

“An enormous shaft of sunlight plunges into the cave like a waterfall. The hole in the ceiling through which the light cascades is unbelievably large, at least 300 feet across. The light, penetrating deep into the cave, reveals for the first time the mind-blowing proportions of Hang Son Doong. The passage is perhaps 300 feet wide, theceiling nearly 800 feet tall: room enough for an entire New York City block of 40-story buildings. There are actually wispy clouds up near theceiling.”