American speleologist Erin Lynch peers down over her shoulder into a giant void of cloud.The floor is over 240m below and although it cant be seen due to the thick cloud that lingers around her, the echo that reverberates several seconds later reminds her of the volume of empty space and her lofty location
'I had never seen anything quite like the inside cloud ladder before,' he said.
'Thick cloud and fogs hangs in the upper half of the cave, where it gets trapped and unable to escape through the small passage in the roof, 250m above the ground.
'It reminded me of being in an abandoned slate quarrying North Wales in bad weather.
The cave system discovered is not the only one with clouds inside, as humidity rises inside the caverns into colder air to form clouds inside the giant, enclosed spaces.

A giant calcite stalactite boss, dwarfs team member Matt Ryan as he looks up at the giant geological feature
The network, includes 'Cloud Ladder Hall' which itself  measures around 51,000 metres squared, while there are rivers and vegetation on the floor of some of its huge caverns.
'Most caves are either accessed by large walking entrance, some require a long deep swim, other may be very vertical in nature where you need ropes to abseil down the walls deep into the caves.
'We had to be aware of high water levels inside the caves, especially when it rained heavily on the surface.
'The drainage catchment to these caves is massive and soon the caves can be extremely dangerous and impassable,' he added.

An explorer scales the rope up a vertical section of cave known as a pit in Xinu Attic



Crystal clear pools and slow moving streams make it easier to explore Quankou Dongs main river passage in the huge network of caves that have not welcomed visitors in years