At 488,100 km2 (188,500 sq mi), Turkmenistan is the world’s 52nd-largest country. It is slightly smaller than Spain and somewhat larger than the US state of California. It lies between latitudes 35° and 43° N, and longitudes 52° and 67° E. Over 80% of the country is covered by the Karakum Desert. The center of the country is dominated by the Turan Depression and the Karakum Desert. Topographically, Turkmenistan is bounded by the Ustyurt Plateau to the north, the Kopet Dag Range to the south, the Paropamyz Plateau, the Koytendag Range to the east, the Amu Darya Valley, and the Caspian Sea to the west. Turkmenistan includes three tectonic regions, the Epigersin platform region, the Alpine shrinkage region, and the Epiplatform orogenesis region. The Alpine tectonic region is the epicenter of earthquakes in Turkmenistan. Strong earthquakes occurred in the Kopet Dag Range in 1869, 1893, 1895, 1929, 1948, and 1994. The city of Ashgabat and surrounding villages were largely destroyed by the 1948 earthquake.

The Kopet Dag Range, along the southwestern border, reaches 2,912 metres (9,554 feet) at Kuh-e Rizeh (Mount Rizeh).[The Great Balkhan Range in the west of the country (Balkan Province) and the Köýtendag Range on the southeastern border with Uzbekistan (Lebap Province) are the only other significant elevations. The Great Balkhan Range rises to 1,880 metres (6,170 ft) at Mount Arlan and the highest summit in Turkmenistan is Ayrybaba in the Kugitangtau Range – 3,137 metres (10,292 ft).The Kopet Dag mountain range forms most of the border between Turkmenistan and Iran.

Major rivers include the Amu Darya, the Murghab River, the Tejen River, and the Atrek (Etrek) River. Tributaries of the Atrek include the Sumbar River and Chandyr River.

The Turkmen shore along the Caspian Sea is 1,748 kilometres (1,086 mi) long. The Caspian Sea is entirely landlocked, with no natural access to the ocean, although the Volga–Don Canal allows shipping access to and from the Black Sea.

Major cities include Aşgabat, Türkmenbaşy (formerly Krasnovodsk), Balkanabat, Daşoguz, Türkmenabat, and Mary.