How explorers found vertical sinkhole cave deep in Vietnam forest

A team of 10 British and Vietnamese cave explorers conducted a 20-day survey in the national park from March 21, and discovered 26 new caves.

Among the most remarkable findings was Cha Ngheo, identified as a vertical sinkhole with its entrance perched atop a mountain and a waterfall cascading inside.

For Howard Limbert, leader of the team and a long-time member of the Royal British Cave Association, the find was exceptional.

After nearly 36 years of exploring caves in central Vietnam, he described Cha Ngheo not as a routine discovery, but as the result of one of the most technically demanding and physically challenging expeditions of his career.

The story began in 2023, when villagers spoke about spotting a cave entrance on a mountaintop with a stream flowing directly inside.

Dense vegetation covered the area, and the slick, unstable terrain made access difficult.

For Limbert and his team, such accounts are often the starting point of discovery, but reaching the site was a challenge.

Howard Limbert recounts his journey exploring Cha Ngheo Cave in Vietnam's Phong Nha - Ke Bang National Park. Photo by VnExpress/Dac Thanh

In March that year, the expedition spent two days trekking to reach the cave entrance. As the team drilled into the rock, a falling stone struck and broke one expert's arm. Limbert said the group had to send a member back to escort the injured explorer to hospital.

Those who remained continued their descent into the shaft. But at around 300 meters, they ran out of rope even as the cave kept plunging deeper.

"We could see there was more to explore, but without enough rope, we had no choice but to turn back," Limbert said.

The expedition came to a premature end.

Returning with resolve

In April 2026, the group came back, better equipped and determined to go further.

This time, the expedition included 13 core members, supported by local guides and porters carrying thousands of meters of rope and other essential supplies.

A rappelling expert descends into Cha Ngheo Cave, which has a waterfall approximately 350 meters high, at Vietnam's Phong Nha - Ke Bang National Park, April 2026. Photo by Oxalis

After another long trek to the remote entrance, the group spent the night suspended in hammocks tied between trees.

The rocky mountaintop offered no flat ground for tents.

At first light, they began their descent.

The cave demanded precision. The initial 90-meter vertical drop required carefully placed anchors. Beyond that, sloping rock faces forced the team to repeatedly drill, secure, and descend in stages.

Every movement was deliberate.

What makes Cha Ngheo Cave extraordinary is its structure. Unlike most caves in Vietnam, which extend horizontally, this one plunges almost straight down.

Water from the surface funnels into the cave, forming a dramatic underground waterfall estimated at 350 meters high.

The sound of rushing water echoed through the shaft, and the temperature dropped sharply as explorers descended.

The entrance to Cha Ngheo Cave, viewed from above. Photo by Oxalis

At around 350 meters, the cave opens into a horizontal passage.

Here, the explorers entered a different world. The passage stretched roughly 600 meters, with sections submerged in cold, fast-moving water.

Progress required swimming through narrow channels, navigating slippery rocks, and working against the current.

Only two members of the team reached the deepest surveyed point at 600 meters before conditions forced them to turn back.

"It was extremely cold, and we didn't have specialized thermal gear," Limbert said.

"We could not stay long."

Even at this depth, the cave had not revealed all its secrets.

Beauty, danger, and scientific value

Cha Ngheo Cave stands out not only for its dramatic vertical form but also for the risks it presents. Harsh conditions, strong water flow, and the constant threat of flooding make it one of the most hazardous caves the team has encountered.

If water levels rise, escape routes could quickly become impassable.

For this reason, Limbert thinks the cave is not suitable for tourism but only for exploration.

Nevertheless, its significance is undeniable.

The cave may be part of a larger, still-hidden system beneath the national park, one that could reshape understanding of the region's subterranean landscape.

With much of the cave still unexplored, the team plans to return in 2027.

For Limbert, the challenge is far from over.

"This is the most difficult cave we've encountered in Vietnam," he said.

"And we still haven't reached the end."