According to Jungle Boss Director Le Luu Dung, after examining Google Earth satellite imagery and spotting an unusually large dark patch, experts from the National Speleological Society and Jungle Boss used drones to conduct a field inspection and pinpoint the sinkhole’s exact location.
A 10-member survey team, including forest rangers, conducted a preliminary expedition in late April 2026 to identify an access route. It was not until the third day that the group reached the rim of the sinkhole.
The main expedition took place from July 23 to 29, involving 24 participants, including experts from the National Speleological Society, Jungle Boss’s technical team and local forest rangers in Quang Tri Province.
The team trekked more than 20 km through dense forest and across sharp, jagged limestone formations, enduring severe water shortages during the dry season, to reach the sinkhole’s rim.
The explorers installed safety systems and abseiled 120 metres down a vertical rock face to measure the sinkhole’s interior. The survey revealed that the cavity is oval-shaped and widens towards the bottom, measuring approximately 250 metres long, 200 metres wide and 120 metres deep.
Safety Director of Jungle Boss Nguyen Van Uy, confirmed that it was one of the largest sinkholes he had encountered in more than 20 years of exploring the forests of Phong Nha-Ke Bang.
Remarkably, the bottom of the sinkhole is home to a thriving, largely undisturbed ecosystem, with numerous towering ancient trees, providing evidence that it formed millions of years ago.
The expedition team also discovered millions of seashells and snail shells piled up along the rock walls, together with numerous monkey skeletons, suggesting that a once-rich ecosystem continues to flourish quietly deep within the chasm.
The survey team searched for geological signs of an underground cave system but found no conclusive evidence. Despite examining the rock walls metre by metre, they discovered only a small crack, five metres high and 12–15 metres deep, with no airflow.
The entire base of the rock walls and the watercourses had been completely buried beneath layers of soil and rock from previous landslides, leaving no visible direct passage.
The discovery provides valuable new insights into the geology, geomorphology, and formation of ancient ecosystems in the heritage area over millions of years.
Jungle Boss has submitted a detailed report to the Management Board of Phong Nha-Ke Bang National Park. The company has also proposed further research across the wider Cha Noi-Khe Gat area and surveys of new access routes from outside the sinkhole.
