Situated at the confluence of the Mekong and Nam On rivers is the Pak Ou cave, usually called Tham Ting. It is actually made up of two caves - the upper cave is known as Tham Theung and the lower cave is Tham Loum.

The upper cave, formerly fitted with doors, contains a multitude of Buddha statues, generally standing, with hands aligned along the body. Most are made of wood or terra cotta. Halfway inside it is a hang lin whose spout is a representation of naga emerging from a dragons mouth. The particular characteristic of the lower cave lies in the presence of limestone animals and deities.

In between the spaces occupied by various altars filled with Buddha statues are images of Hanuman and of a forest-living hermit, Rusi (a very popular figure in Laotian legends) seated in the Javanese manner.