Its longest border is with the Caspian Sea (1,786 km). The other borders are with Iran (to the south, 992 km), Afghanistan (to the south, 744 km), Uzbekistan (to the north and east, 1,621 km) and Kazakhstan (to the north, 379 km). Turkmenistan is slightly larger than California in territory, occupying 488,100 km². By area Turkmenistan ranks fourth among the former Soviet republics, after Russia, Kazakhstan, and Ukraine. The country's greatest extent from west to east is 1,100 km, and its greatest north-to-south distance is 650 km.
Terrain: flat-to-rolling sandy desert with dunes rising to mountains in the south; low mountains along border with Iran; borders Caspian Sea in west. Depressions along the Karakum Desert may be found.
- lowest point: Akjagaýa Depression (Sarygamysh Lake) in north-western Turkmenistan, –81 m (the actual water level in Sarygamysh Lake fluctuate widely from –110 m at its shallowest to –60 m).
- highest point: Aýrybaba, 3,139 m.
Turkmenistan's mountains include 600 km of the northern reaches of the Kopet Dag Range, which it shares with Iran. The Kopet Dag Range is a region characterized by foothills, dry and sandy slopes, mountain plateaus, and steep ravines; Mount Şahşah (2,912 m), also known as Mount Rizeh, southwest of Ashgabat, is the highest elevation of the Kopet Dag Range in Turkmenistan. The Kopet Dag is undergoing tectonic transformation, meaning that the region is threatened by earthquakes such as the one that destroyed Ashgabat in 1948 and registered nine on the Richter scale. The Krasnovodsk and Üstýurt plateaus are the prominent topographical features of northwestern Turkmenistan.
Karakum), which occupies about 350,000 square kilometers (see Environmental Issues). Shifting winds create desert mountains that range from two to twenty meters in height and may be several kilometers in length. Chains of such structures are common, as are steep elevations and smooth, concrete-like clay deposits formed by the rapid evaporation of flood waters in the same area for a number of years. Large marshy salt flats, formed by capillary action in the soil, exist in many depressions, including the Garaşor, which occupies 1,500 square kilometers in the northwest. The Sandykly Desert west of the Amu Darya river is the southernmost extremity of the Qizilqum Desert, most of which lies in Uzbekistan to the northeast.