Today’s Solutions: July 16, 2025

Journey to the center of the Earth
Marco Visscher | October/November 2011 Issue
If someone—a gloomy teenager, a cheerless ex-adventurer—sighs that everything has already been done, every place in the world already traversed, send him or her to Vietnam. The country’s numerous caves are legendary. Seventy years ago, Vietnamese leader Ho Chi Minh planned his resistance to the Japanese invaders and the fight for independence from the French in the Pac Bo cave in northern Vietnam. During the Vietnam War in the second half of the 20th century, caves sheltered thousands of Vietnamese from American bombs. But many of the country’s caves have barely been discovered.
Recently, several British spelunkers discovered the world’s largest cave in a remote section of the Phong Nha-Ke Bang National Park in central Vietnam, near the Laotian border. Hang Son Doong, or “mountain river cave,” belongs to a network of 150 caves that contains a jungle, among other things, and could easily house a 40-story skyscraper. Without the help of local villagers, the British would never have found Hang Son Doong. Jungle native Ho Khanh led the expedition. His father was killed in the Vietnam War, forcing Khanh to fend for himself in the area at a young age. He discovered the entrance to Hang Son Doong as a boy, but he forgot where it was until 2009. The photo shows two explorers swimming in the water of the Hang Ken cave made of flowstone, which forms as water runs down cave walls.
Photo: Helen Flamme via Flickr

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