The resurgence of the Xe Bang Fai river after flowing through Tham Khoun Ex one of the worlds largest caves. Laos, SE Asia. Photographer Braden Gunem.

The Xe Bang Fai River flows underground.

Claire Cripps walks along a 60m long rimstone pool basin in Tham Khoun Xe in Laos. It is the largest known formation in the world.