Take a glimpse inside Hang Sơn Đoòng, the largest known cave on Earth, in this breathtaking video captured by Beijing-based photographer Ryan Deboodt. The massive cave, which is located in Vietnam's Quảng Bình province and measures about 5.5 miles, was created 2 to 5 million years ago after the eroding limestone ceiling of the underground river collapsed.

Despite its immense size, Sơn Đoòng Cave was only discovered in 1991 by a local man seeking shelter from a storm. The cave's existence was largely unknown to the rest of the world until a group of British cavers visited and surveyed the site in 2009. Prior to this discovery, the title for the world's largest cave was held by Malaysia's Deer Cave in Gunung Mulu National Park.

Today, Hang Sơn Đoòng (which translates to "mountain river cave") is characterized by its cool, cloudy microclimate, fossilized passageways, swift underground river, vast caverns and its enormous collection of alien-like stalactites and stalagmites. Perhaps one of the coolest things about the cave, however, is the fact that there is literally a jungle inside of it.

As Deboodt explains in the caption for the photo above, "the light in the background is not an entrance/exit of Hang Son Doong, but it is a doline, or skylight, allowing light in and makes it possible for a jungle to grow inside the cave."

Want to explore this amazing destination for yourself? Oxalis Tours offers a seven-day guided expedition through the heart of Sơn Đoòng, though keep in mind that the difficulty of the expedition requires participants to be in excellent physical shape.

You can explore more of Deboodt's cave expeditions on his Instagram.

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Catie Leary ( @catieleary ) writes about science, travel, animals and the arts.

In world's largest cave, spelunkers look like tiny figurines
Han Son Doong is known for its swift underground river, vast caverns, cloudy micro-climate and, most of all, the jungle that grows within it!