This underground cave system is so large, it has own weather system
Explored in its entirety just last year, Er Wang Dong (meaning “Second Royal Cave”) is an enormous cave system in the Chongquing province of Southwest China. With passages stretching 42,139 metres (138,251 feet) and a maximum depth of 441 metres (1,447 feet), the cave is so large, it has its own lush green forest, crystal clear pools and white water rapids, enormous stalagmites, and oddly enough, clouds.
While local nitrate miners knew there was something big lurking beneath China’s 195-metre-deep Niubizi tiankeng sinkhole, it was only when a team of 15 explorers and photographers from the Hong Meigui Cave Exploration Society plumbed the depths of the sinkhole to access and explore the Er Wang Dong cave system that its sheer size was realised. Until the explorers got there, none of the system’s major underground passages had ever been touched by light.
Formed by limestone dated to the the Ordovician Period, which lasted almost 45 million years, from 488.3 million to 443.7 million years ago, Er Wang Dong is situated near another large cave system called San Wang Dong, with a length of around 67,825 metres.