Combination of mountains (up to 2000 meters at Vietmamese border) and low hills in the east and central; and valley in the south-west where it is divided from Thailand by the Mekong river.

Phu Hin Bun National Biodiversity Conservation Arra (NBCA) occupies more than 1500 square km in the central province, between the highways 13 and 8A. Even though many of the area's wildlife have been killed by hunting and various developement the area is believed to contain some sizable population of endangered animals.

On the eastern side the Nakai-Nam Theun NBCA consists of huge 3700 square km of forested hills and river streams with lot of plant life and wildlife. On the eastern side it borders with Vietnam.

The province contains many limestone mountains, cave systems, and rivers flowing down the mountain slops and through the caves. Tham (cave) Khon Lore at the upper part of Nam Hin Bun river offers a 7 km long waterway navigable by small boat.

The provincial capital Thakhek is on the Mekong river bank. Some buildings from the French colonial era can still be seen. From Thakhek travellers can cross the Mekong river by ferry boat to and from Thailand's Nakhon Phanom. People can also cross border to and from Vietnam at Na Phao checkpoint on the highway no. 12.