Passage III

Uncovering the World’s Largest Cave

[1]

Deep below themountains of central Vietnam lies what could be described as: another world. Located in Phong Nha-Ke Bang National Park, the enormous Hang Son Doong (“Mountain RiverCave”) is believed to be the largest cave in the world. (33) Son Doongis part of a system of 150 caves that snake beneath the ground throughout the region. At roughly five miles long, 300 feet wide, and 660 feet tall, Son Doong is large enough to hold an entire city block of forty-story buildings.

[2]

Even more impressive than the cave’s size, perhaps, such as what grows within it. [A] Portions of Son Doong contain what many envision when they think of caves, which dark chambers ornamented with gigantic calcite formations and populated by colorless creatures that are very unique looking. Other parts of the cave, however, are dramatically different, verdant ferns,palm trees, bamboo, liana vines, and stinging nettles flourish here as well. In fact, researchers have found that the dense subterranean jungle of Son Doong essentially have mirrored the variety of plants and animals in the forest directly aboveground.

[3]

While the abundance of vegetation in Son Doong is possible because of the way the cave formed. Between two and five million years ago, the Rao Thuong River chiseled through the limestone under the range now known as the Annamite Mountains, near Vietnam’s border with Laos. At the top of the cave, colossal“skylights,” measuring up to 300 feet across, that formed when weak portions of the cave’s ceiling collapsed. [B ] The gaps allow sunlight to pass through and nourish the life below. [C]

[4]

Exploring Son Doong is a once-in-a-lifetime experience, but it isn’t easy. Simply hiking there from the nearest village takes more than a day. [D ]Inside the cave, formidable obstacles, such as a 200-foot-high wall covered in mud, make traversing it a major challenge. Still, year after year, Son Doong draws people from around the globe who want to experience what was once a hidden underground world.