The cave contains a dedicated jungle ecosystem within its largest cavern, known as 'Garden of Edam'.
Large calcite pearls, roughly the size of baseballs, have formed in the cave's ancient dried-up pools.
The cave system was created by the Rao Thuong River eroding the limestone along a fault line.
Its volume is estimated at 38.5 million cubic meters, making it the largest in the world by cross-sectional area.
Local man Hồ Khanh accidentally discovered the entrance in 1990, but it remained unexplored by international caving experts until 2009.
The cave maintains its own internal clouds caused by the temperature differential between the cool cave air and the humid outside air.
A wall of calcite named 'The Great Wall of Vietnam' stands 90 meters high, requiring specialized climbing equipment to ascend.
No public trails exist; all access requires a multi-day trek through dense national park terrain.
Fossils estimated to be millions of years old are embedded within the limestone walls of the cave.
Hang Sơn Đoòng is the world's largest natural cave passage by volume, located within the Phong Nha-Kẻ Bàng National Park in Vietnam. The cave measures approximately 9 kilometers in length, with sections reaching 200 meters in height and 150 meters in width. It features a unique subterranean ecosystem, including its own localized weather system, clouds, and a flowing river. Exploration is restricted to guided expeditions conducted by a single licensed tour operator to preserve the fragile cave environment. The interior contains massive stalagmites reaching up to 80 meters, considered among the tallest in the world. Visitors traverse jungle sinkholes known as 'doline' collapses that allow sunlight to penetrate the deep interior, supporting vegetation growth. The cave is situated in a remote, limestone-karst region near the border with Laos. Access requires significant physical fitness for trekking and basic rope-climbing maneuvers. Tours typically limit the number of participants per year to minimize human impact on the ecosystem.
The Doline 1 or 'Garden of Edam' where sunlight illuminates the interior vegetation.
Physical training involving long-distance hiking and elevation gain is mandatory to ensure successful completion.
Bring high-quality, quick-drying hiking gear as you will be frequently crossing underground rivers.
Prioritize waterproof housing for camera equipment due to high humidity and water crossings.
Attempting to locate or enter the cave without an officially licensed guide and permit, which is illegal and dangerous.
Closed annually from September to January due to seasonal flooding risks.
Strict 'leave no trace' policy; all waste must be carried out, and touching formations is prohibited.
