The province includes the Annamite Range, stretching east to Vietnam, while to the west are the Mekong River and Thailand.

[9] The principal river is the Nam Kading, meaning 'water like a bell', a tributary of the Mekong; its catchment covers about 92% of the provincial area.

[9] In Khamkheuth District, there is karst limestone scenery, which is allegedly the largest formation of its type in Southeast Asia.

The rock pinnacles have formed stone forest similar to limestone outcrops in southern China.

[2] At 4,270 square kilometres (1,650 sq mi), Nakai-Nam Theun National Park in Bolikhamsai and Khammouane provinces is the third largest protected area in Laos.

[11] Under the World Wildlife Fund (WWF) Greater Mekong Lao PDR Country Programme, studies have been carried out in the 2 forest areas in the province to assess the degree of sustainable rattan harvest and production as it provides income in whole of the Mekong region to rural villages.

[12] The species sampled were mak naeng (cardamom), bamboo shoots of many species, all year san (Lao lady palm), mushrooms, pak van, kha (galangal), wai houn (Calamus melanochaetes, syn.

[11] The province is made up of the following districts:[2] Laos's largest hydroelectric project, Nam Theun 2 Dam (NT2), began operation in March 2010.