The giant sinkhole lies hidden among the primary forests of the Cha Noi-Khe Gat area in Phong Nha-Ke Bang National Park, in central Vietnam's Quang Tri Province.
Its opening is oval-shaped, measuring about 190 metres by 140 metres. The interior extends more than 250 metres in length, 200 metres in width and 120 metres in depth. Its estimated area is about two hectares, equivalent to three standard football pitches.
The sinkhole floor is completely covered by primary forest. The green canopy acts as effective camouflage, making the vast geological formation almost disappear when viewed from above.
The first clue came from Kevin Ditamore, an experienced member of the US-based National Speleological Society (NSS), who spotted an unusually large dark patch while examining satellite images on Google Earth. Experts pinpointed the sinkhole after three drone flights to investigate the site.
The expedition team installed a safety system and rappelled down the sheer 120-metre rock face to survey the sinkhole floor. Experts said it was among the largest sinkholes they had recorded in Phong Nha-Ke Bang.
Before reaching the site, 24 team members, including cave experts, technical staff and local forest rangers, spent nearly a week trekking more than 20km through dense forest and across sharp, jagged limestone terrain.
At the bottom, the team found enormous limestone boulders scattered across the ground, traces of stalactites on the rock walls and lush vegetation.
Numerous snail shells were also discovered. During the survey, the team heard monkeys calling across the forest canopy, indicating that the sinkhole is not merely a vast geological structure but also encompasses an ecosystem inhabited by wildlife.
The team searched for geological signs that might lead to an underground cave but found no promising evidence. Their inspection identified only a fissure about five metres high and 12-15 metres deep, with no detectable airflow. Landslide deposits had completely buried the base of the walls and the watercourse, leaving no direct passage visible.
“Water here drains through hundreds of tiny holes and fissures rather than concentrating at a single point. So far, we have found no opening of significant size or airflow rising from the bottom of the sinkhole,” Ditamore said.
The discovery could provide important insights into the geology, geomorphology and ancient ecosystem history of the Phong Nha-Ke Bang heritage area, shaped over millions of years.
The expedition team has submitted a detailed report and field measurements to the management board of Phong Nha-Ke Bang National Park. It has proposed further research in the Cha Noi-Khe Gat area and surveys of new access routes from outside the sinkhole.
Beyond the newly discovered formation, Phong Nha-Ke Bang National Park contains hundreds of spectacular caves, many of which have been developed for tourism. Over Cave is one example of the area's striking underground landscapes.
Location of Phong Nha-Ke Bang National Park in Quang Tri Province. (Image: Google Maps)
Photos: Jungle Boss
