1. Son Doong Cave, Vietnam
Son Doong Cave which means ‘cave of the mountain river’ was discovered by a local much before a group of scientists began exploring it in 2009. The thunder of a flowing stream and whistling sound of the wind prevented locals from entering it until British Cave Research Association conducted a survey here. A solutional cave located at Phong Nha-Kẻ Bàng National Park in Quảng Bình Province, Vietnam has a gushing subterranean river inside. This magnificent cavern has been regarded as the largest cave passage cross-section known to the world yet. Exploring Son Doong Cave is an expensive affair and a permit is required, however, it’s worth every penny and effort. Don’t miss it if you have deep pockets and you ever visit Vietnam.
