Journey to the underworld: Exploring the world’s largest cave near Danang - SilverKris

"A colossal subterranean system whose main chamber has the largest cross-section of any known cave, stretching roughly 9 km and housing towering calcite formations, vast stalagmites and stalactites, and two huge dolines that let in shafts of sunlight to support lush underground jungles and a rainforest. Visitors spend multi-day expeditions (including long river crossings, rocky scrambles, subterranean beaches and icy water canyons) and must tackle technical ascents — including a ladder and long rope-and-harness climb — to reach exits. The cave’s scale is frequently compared to parking a Boeing 747 inside the chamber; it was first pushed into wider scientific awareness after a 2009 survey and was originally discovered by a local villager in 1990. Ongoing exploration includes cave-diving attempts to link this system with nearby passages, which could alter measurements of its overall volume." - Joshua Zukas