I was sent this short video via Howard & Deb Limbert recently.  Taken by Ryan Deboodt.

Well worth a watch - obviously some lovely caves in Laos.....

https://vimeo.com/152931507

A very nice video that does justice to a great caving trip.

The cave is better known as Tham Xe Bang Fai.
As well as the huge river passage it is home to the world's largest spiders (see my avatar).