Turkmenistan is a landlocked country in Central Asia, bordering the Caspian Sea to the west, Iran and Afghanistan to the south, Uzbekistan to the north-east, and Kazakhstan to the north-west. It is the southernmost republic of the Commonwealth of Independent States (CIS), the loose federation created at the end of 1991 by most of the Post-Soviet states. The geographic coordinates are between 35°08' and 42°48' north latitude, 52°27' and 66°41' east longitude. Its longest border is with the Caspian Sea (). The other borders are with Iran (to the south, ), Afghanistan (to the south, ), Uzbekistan (to the north and east, ) and Kazakhstan (to the north, ). Turkmenistan is slightly larger than Cameroon in territory, occupying . 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 , and its greatest north-to-south distance is . Physical features Terrain of Turkmenistan consists of a flat-to-rolling sandy desert, the Karakum, with its dunes slowly rising to the south; by the time they reach the border with Iran, they become the mountains known as the Kopet Dag. The Caspian Sea washes the western shores of this mostly arid country. Turkmenistan's average elevation is 100 to 220 meters above sea level, with its highest point being Mount Aýrybaba (3,139 m) in the Köýtendag Range of the Pamir-Alay chain in the south-east, and its lowest point being the Akjagaýa Depression in Sarygamysh Lake, close to 100 meters below sea level (the actual water level in Sarygamysh Lake fluctuates widely from –110 m at its shallowest to –60 m). Mount Arlan rises sharply above sea level in the Great Balkhan Range in western Turkmenistan (Balkan Province), and has a topographical prominence only slightly shorter than its height. Nearly 80% of the republic lies within the Turan Depression, which slopes from south to north and from east to west. 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