Hang Son Doong Cave

Hang Son Doong is a cave located within the boundaries of Phong Nha-Ke Bang National Park in Quang Binh Province, Vietnam, and is recognized as the largest natural cave in the world. With a volume of 38.5 million cubic meters, it was officially certified by Guinness World Records in 2013.

Cave was discovered in 1990 by a local farmer named Ho Khanh while seeking shelter from a storm during a hunting expedition in the Phong Nha forest. However, due to the challenging terrain conditions its location was forgotten until it was rediscovered in 2009 by a team led by British caver Howard Limbert, who then conducted a detailed mapping of the site.

The name "Son Doong" consists of two words: "Son" means "mountain" while "Doong" is the name of the valley where the cave is located. This valley is inhabited by the Bru Van Kieu ethnic minority and is the source of the Thuong River. Additionally "Doong" also refers to a cave containing an underground river within limestone mountains.

^{Hang Son Doong Cave (Source:} Local Vietnam⁾

Hang Son Doong is larger and more unique than any other cave in the world in terms of size and internal structure.

• Total Length: 9.4 km
• Width: 175 metres
• Height: 503 metres
• Volume: 38.5 million m³

This size makes it five times larger than Deer Cave in Malaysia, previously considered the world’s largest cave with a volume of 9.5 million m³. Inside, there are spaces wide enough to accommodate skyscrapers of up to 40 storeys.

One of the most remarkable features of Hang Son Doong is its own internal ecosystem and microclimate. The cave’s interior structure generates a unique air circulation and cloud formation due to rainwater seeping from above and air movement within the cave. This condition results in constantly changing atmospheric conditions inside the cave.

• Large collapse areas (dolines): These allow sunlight to penetrate the cave, enabling the development of a unique rainforest ecosystem within.
• Huge stalactites and stalagmites: Massive limestone formations reaching over 80 metres in height.
• Underground river and lakes: A river flows through the cave and has not yet been fully explored; some sections of the cave remain submerged.
• Endemic cave species: Blind fish, freshwater shrimp, bats, monkeys and exotic bird species live inside and around the cave.

^{Hang Son Doong Cave (Source:} Local Vietnam⁾

In addition to its immense size, Hang Son Doong contains unique natural formations found nowhere else. Among the most notable are:

• Watch Out for Dinosaurs: A large collapse area distinguished by its vegetation and geological features.
• Garden of Edam: An ecosystem formed within a massive collapse area, hosting one of the largest forests inside the cave.
• Cave Pearls: Large calcite spheres formed by the aggregation of sand and minerals in certain parts of the cave.
• Underwater Waterfalls and Lakes: Natural water basins formed in specific sections of the cave.

Recognized by Guinness World Records in 2013 as the world’s largest natural cave, Hang Son Doong has become a major site of discovery for the scientific community and nature enthusiasts. However, due to its fragile ecosystem, the Vietnamese government permits only a limited number of visitors.

• Cave tourism is organized exclusively by Oxalis Adventure.
• A maximum of 1,000 visitors are allowed annually.
• Tours last four days and three nights and cost approximately USD 3,000 per person.
• Mass tourism has been prohibited to protect the cave, and a sustainable tourism model that minimizes environmental impact has been adopted.

To reach Hang Son Doong, visitors must fly to Dong Hoi, the nearest city, and then travel by road to Phong Nha-Ke Bang National Park.