They were amazed to discover the entrance to the hidden Er Wang Dong cave system and were stunned when they managed to climb inside to see a space so large that it can contain a cloud.
Photographer and caver Robbie Shone, from Manchester, was part of a team of 15 explorers on a month-long expedition that discovered the hidden system.
‘A few of the caves had previously been used by nitrate miners, at the areas close to the entrance, but had never been properly explored before,’ he said.
‘All the major passageways were deep underground and had never seen light before.