Fewer people have seen the inside of Hang Son Doong in Vietnam than have reached the summit of Mount Everest. This magnificent cave located in the Quang Binh province near the Laos-Vietnam border stands 500 feet tall, 650 feet wide, and stretches 5 1/2 miles in length. As the world’s largest cave, it is so epic in scale that a 747 airplane could fly through its largest cavern, and a New York city-block of 40 skyscrapers could fit inside. To arrive at the cave, adventurers must endure two days of intense jungle trekking and river crossings – this is no day trip! A 7-day expedition with porters, guides, and up to 9 other explorers is to be expected to allow time for the intense hikes to get to the cave, not to mention the activities inside. Once in Hang Son Doong, to reach the end of the cave, visitors abseil, climb, crawl and swim through underground rivers.

It was discovered accidentally in 1990 by local farmer, Ho Khanh, who was seeking shelter from a passing storm. Ho Khanh could not find the entrance again and the cave was lost for nearly eighteen years until he rediscovered the entrance in 2008. The following year led to rediscovery by British cavers. During their initial discoveries, progress was put on hold once the cavers were stopped by an incredible 60-meter (200 ft.) high calcite wall, aptly named the Great Wall of Vietnam. Punctuated by 2 large dolines (areas where the ceiling collapsed), sunlight shines into sections of the cave and offers life to trees and other vegetation.

The cave was created 2 to 5 million years ago when weakened limestone gave way to river water erosion. The massive ceiling collapsed creating huge natural skylights, which offer stunning light shows among the extraordinary topography. A dream for any photographer. This awe-inspiring cave offers some of the world’s tallest stalagmites at up to 80 meters high, immense cave pearls, and breathtaking rimstone pools. Son Doong cave translates to mountain river cave as it rests beneath the Annamite Mountains in central Vietnam.

Since 2009, expeditions to the cave have begun and cavers, photographers and adventurers alike trek there to bask in its secret, untouched ecosystem. It has been open to the public since 2013 with support from incredible guides, who take the most avid trekkers through the hundreds of cave systems inside. The cave is so large that it has its own ecosystem, jungle, river and weather patterns, complete with clouds and fog. Once inside, it is hard to imagine yourself still on earth.