Caspian Sea

From New World Encyclopedia
Caspian Sea viewed from orbit

The Caspian Sea (Russian: Kaspiyskoye More; Persian: Daryaye Khezer) is a landlocked endorheic (having no natural outflow except evaporation) sea between Asia and Europe. It is the world's largest inland body of water, with a surface area of 371,000 square kilometers (143,000 square miles) and a maximum depth of about 980 meters (3,200 feet), and has characteristics common to both seas and lakes. It is often listed as the world's largest lake, though it is not a freshwater one. The Caspian Sea is bordered by five countries, Iran, Russia, Azerbaijan, Turkmenistan, and Kazakhstan. Three major rivers—the Volga, Ural, and Terek—and numerous smaller rivers flow into the Caspian.

Four-fifths of the world’s catch of sturgeon, which yield eggs that are processed into caviar, come from the Caspian Sea. In recent years dessication of spawning grounds, pollution, the damming of rivers, and overfishing have threatened the sturgeon population.

Exploitation of large oil and natural gas reservoirs under the Caspian Sea began in the 1920s, and expanded after World War II, making the area a focus of international politics.

Geography and Topography

The Caspian Sea lies east of the Caucasus Mountains and dominates the flat expanses of western Central Asia. Approximately 20 percent of the southern shoreline borders Iran/Persia (Guilan, Mazandaran and Golestan provinces) at the foot of the Elburz Mountains; the remainder of the shoreline is bordered by Russia (Dagestan, Kalmykia, Astrakhan Oblast), Azerbaijan, , Turkmenistan (Balkan Province), and Kazakhstan, with the central Asian steppes to the north and east. On its eastern Turkmen shore is a large embayment, the Kara Bogaz Gol. The sea is connected to the Sea of Azov by the Manych Canal.

The narrow, elongated basin of the Caspian Sea extends for almost 750 miles (1,200 kilometers) from north to south, with an average width of only 200 miles (320 kilometers). Its area is approximately 149,200 square miles (386,400 square kilometers). Three major rivers flow into the Caspian: the Volga, Ural, and Terek, all of which enter from the north; their combined annual flow makes up 88 percent of all river water entering the sea. The Sulak, Samur, Kura, and a number of smaller rivers flow in on the western littoral, contributing about seven percent of the flow; the remainder comes in from Iranian rivers. The eastern littoral is notable for an absence of any permanent streams.

There as many as fifty islands in the Caspian sea, most of them small. The largest is Chechen, in the northwest, followed by Tyuleny, Morskoy, Kulaly, Zhiloy, and Ogurchin.

Based on the formations of the sea bed and hydrologic characteristics, the Caspian basin is usually divided into the northern, middle, and southern Caspian. The flat, sedimentary plain of the north Caspian, which lies in a moderate continental climate zone, is the shallowest portion of the sea, with an average depth of 13 to 20 feet (4 to 6 meters). An irregular depression, with an abrupt western slope and a gentler eastern gradient forms the middle Caspian. The south Caspian contains a depression reaching a maximum depth of 3,363 feet (1,025 meters). The middle and south Caspian lie in a moderately hot climate, and evaporation from the surface of the sea reaches as much as 40 inches (1,000 millimeters) per year.

The northern part of the Caspian freezes during the winter, and in particularly harsh winters, the whole northern area of the sea is covered with ice. Ice can occur in the southern regions of the sea in December and January. In mild winters, ice forms in shoals in the shallow areas near the coast.

Characteristics and Ecology

The Volga River (about 80 percent of the inflow) and the Ural River discharge into the Caspian Sea, but it is endorheic; there is no natural outflow (other than by evaporation). Thus the Caspian ecosystem is a closed basin, with its own sea-level history independent of the eustatic level of the world's oceans. The Caspian became landlocked about 5.5 million years ago. The level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians claim that a medieval rising of the Caspian caused the coastal towns of Khazaria, such as Atil, to flood. In 2004, the water level was 28 meters (92 feet) below sea level.

Over the centuries, Caspian Sea levels have changed in synchronicity with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic Oscillation. Thus levels in the Caspian Sea relate to atmospheric conditions in the North Atlantic thousands of miles to the north and west. These factors make the Caspian Sea a valuable place to study the causes and effects of global climate change. During the twentieth century, the sea level was also affected by the construction of reservoirs on the Volga River and by the diversion of river-water for irrigation and industry.

The last short-term sea-level cycle started with a sea-level fall of three meters from 1929 to 1977, after which it rapidly rose three meters from 1977 until 1995, possibly because of changing weather patterns that increased precipitation. The rising seas flooded many areas that had become populated during the years of its decline. Since then, smaller oscillations have taken place and have caused major environmental problems.


Depending on the inflow of fresh water from its effluents, the Caspian Sea is a freshwater lake in its northern portions. It is more saline on the Iranian shore. The largely dried-up Garabogazköl embayment routinely exceeds oceanic salinity. The water of the Caspian Sea contains three times less salt than oceanic water. Its salinity is attributed to its origin as an ancient ocean, named Tethis, which connected to the Atlantic and Pacific oceans fifty to sixty million years ago. As the gradual shift of continental plates gradually isolated it, the influx of fresh water from rivers, melting ice and precipitation diluted the salinity of the Caspian.


In the north, the shores of the Caspian are low and composed mostly of alluvial materials washed down by the Volga, Ural, and Terek rivers. The western shore of the middle Caspian is hilly. A narrow marine plain separates the Caspian from the foothills of the Greater Caucasus Mountains. The city of Baku is located on the Abseron peninsula, which juts into the sea north of the Kura-Aras Lowland, formed by the floodplain of the Kura and Aras rivers. On the south and southwest, the Caspina is bordered by the Talish and Elburz mountains. The eastern shore of the southern Caspian is low and formed of sediments laid down by wave action. The eastern side of the middle Caspian is steep, formed by the erosion of the Tupqaraghan and Kendyrli-Kayasansk limestone plateaus. A man-made sandy embankment now isolates the Garabogazköl embayment.

Cities near the Caspian Sea

Major cities by the Caspian Sea:

  • Baku, Azerbaijan
  • Astara, Azerbaijan
  • Lenkeran, Azerbaijan
  • Sumqayit, Azerbaijan
  • Neft Daslari, Azerbaijan
  • Xacmas, Azerbaijan
  • Astrakhan, Russia
  • Derbent, Russia
  • Bandar Anzali, Iran
  • Chalous, Iran
  • Turkmenbashi, Turkmenistan (formerly Krasnovodsk)
  • Atyrau, Kazakhstan (formerly Guriev)
  • Aktau, Kazakhstan (formerly Shevchenko)


The Caspian Sea viewed from Baku, Azerbaijan

The sea is estimated to be about 30 million years old. It became landlocked about 5.5 million years ago. Discoveries in the Huto cave near the town of Behshahr, Iran, suggest human habitation of the area as early as 75,000 years ago.

In classical antiquity it was called the Hyrcanian Ocean. It has also been known as the Khazar Sea. In Persian antiquity, as well as in modern Iran, it is known as the Mazandaran Sea. Old Russian sources call it the Khvalyn (Khvalynian) Sea after the Khvalis, inhabitants of Khwarezmia. Ancient Arabic sources refer to Bahr-e-Qazvin – the Qazvin Sea. In fact, the word "Qazvin" is derived from Caspian.

Historical cities by the sea include

  • Hyrcania, Persia (Iran)
  • Tamisheh, Persia
  • Atil, Khazaria
  • Khazaran


Approximately 850 animal species and more than five hundred plant species are represented in the Caspian. This number of species is relatively low for a body of water of this size. Many species are unique to the Caspian. Blue-green algae (cyanobacteria) and diatoms constitute the greatest biomass concentrations, and there are several species of red and brown algae. Animal life includes fish species such as sturgeon, herring, pike, perch, and sprat; several species of mollusks; and a range of other marine organisms including sponges. Mammals include fifteen species of Arctic seal, and Mediterranean seals. The Caspian seal (Phoca caspica, Pusa caspica in some sources), one of very few seal species living in inland waters, is endemic to the Caspian Sea. In recent centuries, barnacles, crabs, and clams, have entered the Caspian on sea vessels, and gray mullets have been deliberately introduced by humans.



The Caspian holds great numbers of sturgeon, which yield eggs that are processed into caviar. Four-fifths of the world’s catch of sturgeon come from the Caspian Sea. In recent years dessication of spawning grounds, pollution, the damming of rivers, and overfishing have threatened the sturgeon population to the point that environmentalists advocate banning sturgeon fishing completely until the population recovers. A number of measures have been undertaken to protect the sturgeon population, including aquaculture and the prohibition of sturgeon fishing in the open sea. However, prices for sturgeon caviar are so high that fishermen can afford to pay bribes to authorities to look the other way, making regulations in many locations ineffective. Caviar harvesting further endangers the fish stocks, since it targets reproductive females.

A seal industry also has been developed in northern regions.


Exploitation of oil and natural gas reservoirs began in the 1920s, and expanded after World War II. Oil is extracted from the sea bed using drilling platforms and artificial islands. Large reserves lie under the northeastern Caspian and its adjacent shores. Natural gas supplies are also in evidence, though further exploration is needed to define their full potential. Since 1992, Azerbaijan and Kazahkstan have seen an increase of 70 percent in their production of oil. Despite this, the total regional production of 1.6 million barrels (250,000 cubic meters) per day (roughly equal to production of oil in Brazil) is still less than its potential output, and is expected to triple by 2010.

The extraction of such minerals as sodium sulfate from the Garabogazköl also is of considerable economic importance.


As the only coast in Azerbaijan, Kazakhstan and Turkmenistan, the Caspian Sea is a popular destination for domestic tourists. In Iran, the Caspian coast offers sandy beaches, lush vegetation, and spectacular natural scenery which provide a refreshing contrast to city life and the dry interior; the three provinces of Gilan, Mazandaran and Golestan are studded with resort complexes, leisure facilities and holiday homes. The milder winters and warm summers, as well as its accessibility also make the Caspian coast a favorite vacation spot for Russians.

International Disputes

There are three major issues regulated by the Caspian Sea status: access to mineral resources (oil and natural gas), access for fishing, and access to international waters (through Russia's Volga River and the canals connecting it to the Black Sea and Baltic Sea). Access to the Volga River is particularly important for the landlocked states of Azerbaijan, Kazakhstan and Turkmenistan.

If a body of water is labeled as "sea" then there would be precedent to international treaties obliging the granting of access permits to foreign vessels. If a body of water is labeled merely as a lake, there are no such obligations.

  • According to a treaty signed between the Persian Empire (predecessor of today's Iran) and the Russian Empire, the Caspian Sea was technically a lake and it was to be divided into two sectors (Persian and Russian), but the resources (then mainly fish) would be commonly shared. The line between the two sectors was to be seen as an international border in a common lake (like Lake Albert). Also the Russian sector was sub-divided into administrative sectors of the four littoral republics.
  • After the dissolution of the Soviet Union, not all of the newly independent states assumed continuation of the old treaty. At first Russia and Iran announced that they would continue to adhere to the old treaty (but they no longer had a common border), but Kazakhstan, Azerbaijan, and Turkmenistan announced that they did not consider themselves parties to this treaty.
  • This was followed by some proposals for common agreement among all littoral states about the status of the sea:
    • Azerbaijan, Kazakhstan, and Turkmenistan insisted that the sectors should be based on the median line, giving each state a share proportional to the length of its Caspian coastline. Each sector would form part of the sovereign territory of that particular state (making the borders international and also allowing each state to deal with all resources within its sector unilaterally).
    • Iran insisted that the sectors should be such that each state gets a share of one fifth of the whole Caspian Sea. This was advantageous to Iran, because it has a proportionately smaller coastline.
    • Russia proposed a compromise: the seabed (and thus mineral resources) would be divided along sectoral lines; the surface (and thus fishing rights) would be shared among all the states (with the following variations: the whole surface could be commonly shared; or each state would have rights to an exclusive zone, with a single common zone in the center to be shared. The second proposal was deemed impractical, because of the small size of the whole sea).

Current situation

In 2003, Russia, Kazakhstan and Azerbaijan reached an agreement concerning their sectors, which covers 64 percent of the Caspian Sea. There are no problems between Kazakhstan and Turkmenistan, but the latter is not actively participating in the agreement. Azerbaijan is at odds with Iran over oil fields claimed by both states, and there have been incidents of Iranian patrol boats opening fire on vessels sent by Azerbaijan for exploration of the disputed region. There are similar tensions between Azerbaijan and Turkmenistan over the amount of oil pumped from a field recognized by both parties as shared. The southern part of the sea remains disputed.

  • Russia and Kazakhstan signed a treaty, according to which they divided the northern part of the Caspian Sea between them into two sectors along the median line. Each sector is an exclusive zone of its state. Thus all resources, seabed and surface are exclusive to the particular state.
  • Russia and Azerbaijan, and Kazakhstan and Azerbaijan signed similar treaties concerning their common borders.
  • Iran doesn't recognize the bilateral agreements between the other littoral states, but this has limited practical implications, because it doesn't have common borders with Russia and Kazakhstan. Iran continues to insist on a single multilateral agreement among all five littoral states, as the only way to acquire dominion over one fifth of the Caspian Sea.
  • The position of Turkmenistan is unclear.

The Russian sector has been fully defined. The Kazakhstan sector has not been fully defined, but is not disputed. Azerbaijan's, Turkmenistan's and Iran's sectors are not fully defined. It is unclear whether vessels from Azerbaijan and Kazakhstan have been given access to the Volga under their agreements with Russia, and under what conditions vessels from Turkmenistan and Iran are allowed access.

ISBN links support NWE through referral fees

  • Ascher, William, and N. S. Mirovitskaia. 2000. The Caspian Sea: A quest for environmental security. Dordrecht: Kluwer Academic Publishers. ISBN 0792362187
  • Bahgat, Gawdat. 2003. American oil diplomacy in the Persian Gulf and the Caspian Sea. Gainesville: University Press of Florida. ISBN 0813026393
  • Butler, William Elliott. 1971. The Soviet Union and the law of the sea. Baltimore, MD: Johns Hopkins University Press. ISBN 0801812216
  • Klare, Michael T. 2001. Resource wars: The new landscape of global conflict. New York: Metropolitan Books. ISBN 0805055754
  • Kobori, Iwao, and Michael H. Glantz. 1998. Central Eurasian water crisis Caspian, Aral, and Dead seas. Tokyo: United Nations University Press. ISBN 0585116636
  • Stolberg, F. V., David Souter, Eva Lövbrand, and Niklas Holmgren. 2006. Caspian Sea. Kalmar, Sweden: University of Kalmar on behalf of United Nations Environment Programme.

External links

All links retrieved November 29, 2023.


New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.