On a world map the Caspian Sea looks like a lake that forgot to stop growing. It has no outlet to the ocean, yet it is salty, it has waves and storms, and it is shared by five countries. The secretariat of the treaty that protects it describes it as the largest enclosed body of water on Earth.
The five countries on its shores
Going clockwise from the north-west, the Caspian is bordered by:
- Russia, on the north-western shore, including the Volga delta and the republic of Dagestan.
- Kazakhstan, on the long northern and north-eastern coast.
- Turkmenistan, on the eastern shore.
- Iran, along the southern coast below the Alborz mountains.
- Azerbaijan, on the western shore, with Baku on the Absheron Peninsula.
Those five states signed the Framework Convention for the Protection of the Marine Environment of the Caspian Sea, known as the Tehran Convention after the city where it was adopted in 2003. According to its secretariat, it is the first legally binding regional agreement signed by all five littoral states, and it entered into force on 12 August 2006.
Sea or lake
The question sounds academic, but it has practical consequences. International law treats seas and lakes differently when it comes to dividing the seabed, fishing rights and pipelines. The five states have negotiated over the status of the Caspian for decades. For a map reader, the useful point is that the water is brackish rather than fresh, and that the Caspian sits in a basin with no natural link to the open sea.
Three parts, north to south
- The northern Caspian is shallow, fed by the Volga and the Ural rivers, and its surface often freezes in winter. Its waters are the least salty.
- The middle Caspian, off Dagestan, Azerbaijan and western Kazakhstan, deepens toward a central basin.
- The southern Caspian, off Iran and southern Azerbaijan and Turkmenistan, is the deepest part, with a steep slope below the Iranian coast.
The Absheron Peninsula, which juts into the sea at Baku, roughly marks the boundary between the middle and southern basins.
The Volga and the other rivers
Most of the Caspian’s water comes from the Volga, Europe’s longest river, which reaches the sea through a huge delta south of Astrakhan. Other rivers add smaller amounts: the Ural on the Kazakh side, the Terek and the Kura on the western shore, and short rivers from the Alborz in Iran. Because nothing flows out, the level of the sea depends on the balance between river inflow and evaporation, and it has risen and fallen over the past century.
Kara-Bogaz-Gol
On the Turkmen coast a narrow strait opens into Kara-Bogaz-Gol, a large lagoon where water evaporates fast and leaves salt behind. It is one of the oddest shapes on the map of the Caspian, and it shows how sensitive the whole basin is to changes in water level.
Five shores, five climates
The five coasts barely look like the same sea. The northern shore, in Russia and Kazakhstan, is flat steppe and semi-desert, cut by reed beds and river channels. The eastern shore in Turkmenistan and southern Kazakhstan is desert, with cliffs and salt flats. The western shore around Baku is dry and rocky. The Iranian coast is the exception: the Alborz mountains trap moisture from the sea, so the provinces of Gilan and Mazandaran are green, rainy and covered with rice fields, tea gardens and forest. On a satellite image, that narrow green strip below the mountains stands out against the brown land on every other side.
Ports and coastal cities
- Baku, the capital of Azerbaijan, the largest city on the sea.
- Astrakhan and Makhachkala in Russia.
- Aktau in Kazakhstan.
- Turkmenbashi in Turkmenistan.
- Bandar Anzali and other ports on the Iranian coast.
Ferries and cargo ships link the eastern and western shores, part of the trade routes that connect Central Asia with the Caucasus and Europe without crossing Russia or Iran.
Oil, gas and sturgeon
The Caspian region is known for two things that rarely share a map: oil and caviar. Oil has been pumped around Baku since the nineteenth century, and offshore fields lie in several national sectors. The sea is also home to sturgeon, the fish whose eggs are sold as caviar. The Tehran Convention covers pollution from all sources as well as the preservation, restoration and protection of the sea’s species and habitats.
Reading the Caspian with neighbouring regions
The western shore belongs to the region described in the map of the Caucasus, while the eastern shore opens onto the steppes and deserts of the map of Central Asia. Iran’s northern coast links the sea to the map of the Middle East, and the Volga connects it to the plains shown on the map of Eastern Europe.
The Tehran Convention secretariat explains the treaty, its history and its protocols on its About the Tehran Convention page.
