Science
Vietnam’s Son Doong Cave Revealed as World’s Largest Single Passage After Ho Khanh’s 1990 Discovery
In December 1990, Ho Khanh, a local man searching for agarwood in the forests of central Vietnam, was forced to take shelter beneath a cliff during heavy rains. While hiding, he noticed cold air and mist pouring from an opening. He later described the sight to Oxalis Adventure, and the discovery eventually reached Howard Limbert, a British caver exploring the area.
Khanh attempted to locate the entrance again in 2007 but could not find it. He returned alone in 2008, successfully marked the location, and remembered a route that could lead explorers to the cave.
In 2009, a British‑Vietnamese caving expedition led by Limbert explored the cave and surveyed its chambers. The team confirmed that Son Doong is the world’s largest known single cave passage, with dimensions of about 200 metres in height, 150 metres in width, and extending at least 6.5 kilometres, as recorded by Guinness World Records.
The cave, located in Phong Nha‑Ke Bang National Park, contains towering rock formations, an underground river, and vegetation that grows in areas where sunlight enters through collapsed sections of the ceiling, creating an underground jungle. The cave’s formation is believed to date back millions of years, when water eroded limestone and later roof collapses opened large chambers to the sky.
The discovery brought international attention to the Phong Nha‑Ke Bang region. Due to its remote location, difficult terrain, and fragile formations, access requires careful planning. Organized expeditions began allowing visitors into Son Doong in 2013, offering guided treks through forest terrain and the cave’s extensive chambers.
Ho Khanh’s initial search for agarwood and subsequent discovery of Son Doong illustrate how curiosity and chance can reveal natural wonders that remain hidden beneath forests and limestone mountains.