Hang So Doong

Hang Son Doong Cave, within the boundaries of Quang Binh Province in central Vietnam, lies the Phong Nha-Ke Bang National Park. place was discovered in 2009 through scientific exploration and has since been recognized in literature as the world’s largest known natural cave. It is one of the most significant caves in terms of geology, biology and environment sciences, due to its volumetric scale and ecosystem characteristics.

Cave was first accidentally discovered in 1991 by a local farmer named Ho Khanh, but its entrance could not be relocated for over a decade due to dense vegetation and steep terrain. In 2009, a specialist team from the UK-based British Cave Research Association, guided by Ho Khanh, successfully located the cave and conducted a comprehensive scientific exploration.

This discovery revealed the cave’s physical dimensions, morphological structure and ecological potential day.

(Hang Son Doong Cave, National Geographic)

The total length of Hang Son Doong is approximately 9 kilometres, with some sections reaching heights of 200 metres and widths of 150 metres.

The cave formed around 2 to 5 million years ago through the erosion of limestone layers in the region. An active underground river flowing through it played a decisive role in shaping both its formation and current structure. Collapses in the ceiling created two large dolines (collapse sinkholes), allowing sunlight to penetrate the interior and enabling the development of ecosystems within the cave.

The cave’s unique microclimatic conditions have fostered the development of a distinct ecosystem. Sunlight filtering through ceiling collapses has enabled the growth of forested areas inside the cave, locally known as the “Garden of Edam,” and the establishment of a complex plant cover.

These areas are believed to host endemic species that have evolved differently from those found outside the cave. High humidity and stable temperature such as factors have rendered the cave ecosystem sensitive and in need of protection building.

Hang Son Doong was opened to limited tourism under controlled ecotourism conditions in 2013. The annual number of visitors is capped to preserve ecological balance. Tourist activities are permitted only between January and August, while the cave remains closed during the September-December period due to flooding.

Guiding authority has been granted exclusively to the licensed company Oxalis Adventure, and all activities are conducted within the framework of environmental protection protocols. Thanks to these measures, the cave’s natural integrity has been preserved while enabling sustainable tourism harm.

For individuals unable to visit physically, Oxalis Adventure has developed a high-resolution virtual tour. Using 360 degree imaging technology, this application allows users to explore the cave’s interior in intricate detail. This virtual tour is offered free of charge for both tourism and educational purposes.