Hundreds of cave pearls in various colors and shapes have been discovered deep inside Hung Cave, part of the Hung Thoong cave system, creating a remarkable underground landscape in the core zone of Phong Nha - Ke Bang National Park.

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Cave pearls are a unique type of speleothem that form in spherical, oval or slightly flattened shapes. Photo: Uy Jang Jong

Cave pearls are a unique type of speleothem that form in spherical, oval or slightly flattened shapes. They develop when calcium-rich water droplets fall from cave ceilings onto mineral deposits on the cave floor over extended periods. Their size can range from as small as a pea to as large as a baseball.

According to Nguyen Van Uy, deputy director of Jungle Boss Co., Ltd., Phong Nha - Ke Bang is home to more than 400 caves of varying sizes, but cave pearls have been recorded in only a handful of them.

"Cave pearls have been found in Over Cave, Son Doong Cave and Hung Cave. However, Hung Cave contains a much larger concentration, with bigger pearls distributed in clusters across the cave floor," Uy said.

Inside Hung Cave, cave pearls are primarily found around small calcium-rich pools in the deeper sections of the cave. The pearls are round or oval in shape, with smooth surfaces and colors ranging from white to pale yellow depending on the mineral composition of the water seeping through the cave ceiling.

Notably, hundreds of cave pearls are concentrated within an area measuring only two to three square meters, forming what appear to be natural pearl nests on the cave floor. Experts say this is one of the cave formations that takes the longest time to develop in limestone cave environments and is typically associated with large cave systems.

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Hundreds of cave pearls are concentrated within an area measuring approximately two to three square meters, forming natural "nests" on the cave floor. Photo: Uy Jang Jong

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Depending on the mineral content of the water, cave pearls can appear white or yellow. Photo: Uy Jang Jong

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The smooth, rounded pearls add to the mysterious beauty of the underground landscape. Photo: Uy Jang Jong


"Depending on the mineral content of the water, cave pearls may appear white or yellow. This type of formation develops over an exceptionally long period and holds significant geological and scenic value," Uy added.

Although cave pearls are not gemstones and have no commercial value, they are highly regarded for their scientific and aesthetic importance. Their smooth, rounded surfaces and subtle luster contribute to the mysterious beauty of natural cave environments.

Experts note that cave pearls can only remain stable within cave environments. Once removed, changes in temperature, humidity and physical conditions can cause them to crack, deteriorate or lose their color.

Hung Cave, part of the Hung Thoong cave system, was discovered in 2002 and opened for adventure tourism in early 2023. To preserve its geological heritage, tour operators and local authorities strictly prohibit visitors from touching or disturbing cave pearls or other speleothem formations inside the cave.

Hai Sam