Xiangkhouang Province
Bolikhamsai Province covers an area of . Bolikhansai Province borders Xiangkhouang Province to the northwest, Vietnam to the east, Khammouane Province to the south, and Thailand to the west. The province includes the Annamite Range, stretching east to Vietnam, while to the west are the Mekong River and Thailand. At , the Nakai-Nam Theun National Park in Bolikhamsai and Khammouane Provinces is the third largest protected area in Laos.