GO NOW
Son Đoòng Cave, Vietnam
This showstopper in central Vietnam is widely recognised as Earth’ s largest known cave passage by volume. It’ s found in the jungles of Phong Nha-Ke Bang National Park near the Laos border, and is so vast that it has its own microclimate.
At nearly 5.6 miles long and with a volume of around 1.36 billion cubic feet, Son Đoòng formed over millions of years as underground rivers dissolved the ancient limestone beneath the Annamite Mountains. When the roof collapsed in places, it created enormous skylights known as dolines, which allowed for trees and ferns to grow inside. More than 200 plant species have been recorded here, along with several newly identified cave-adapted animals, including blind and transparent creatures. It also contains some of the world’ s tallest known stalagmites, with formations rising more than 260 feet from the cave floor.
The cave was first found in 1990 by local man Ho Khanh, who heard the roar of an underground river while sheltering from a storm. He lost track of the location, but found it again in 2008, and the following year led a British-Vietnamese expedition to the site to confirm its extraordinary scale.
Today, access is tightly controlled, and visits are run as multi-day cave-camping expeditions that involve jungle trekking, river crossings and the ascent of the so-called Great Wall of Vietnam, a 295-foothigh calcite barrier. Numbers are limited to protect the fragile ecosystem, and tourism pauses during the wettest months, when underground rivers can rise rapidly.
fall 2026 • 11