Instruct: Given a question, retrieve documents that answer the question.
Query: How large is the Caspian Sea?
The wide and endorheic Caspian Sea has a north–south orientation and its main freshwater inflow, the Volga River, enters at the shallow north end. Two deep basins occupy its central and southern areas. These facts lead to horizontal differences in temperature, salinity, and ecology. The Caspian Sea spreads out over nearly 750 miles (1,200 km) from north to south, with an average width of 200 miles (320 km). It covers a region of around 149,200 square miles (386,400 square km)—bigger than the region of Japan—and its surface is about 90 feet (27 meters) below sea level. The sea bed in the southern part reaches as low as 1,023 m (3,356 ft) below sea level, which is the second lowest natural depression on earth after Lake Baikal (−1,180 m, −3,871 ft). The ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its saltiness and large size.
The Black Sea-Caspian Steppe is an informal name for that part of the Eurasian Steppe that extends south between the Black and Caspian Seas. It is usually treated as part of the Pontic-Caspian steppe which includes the area north of the Black and Caspian Seas, but there is some reason to treat it as a distinct place. Its natural boundaries are the Sea of Azov and Black Sea on the west, the Caucasus Mountains on the south and the Caspian Sea on the east. Its northern boundary may be taken as the triangle formed by the lower Don River and Volga River which are about 60 km apart to the west of Volgograd. This article excludes the north slope of the Caucasus which is not steppe and has a distinct geography and history.
Archeological studies of Gobustan petroglyphs indicate that there once had been dolphins and porpoises,[21][22] or a certain species of beaked whales[23] and a whaling scene indicates large baleen whales[24] likely being present in Caspian Sea at least until when the Caspian Sea ceased being a part of the ocean system or until the Quaternary or much more recent periods such as until the last glacial period or antiquity.[25] Although the rock art on Kichikdash Mountain is assumed to be of a dolphin[26] or of a beaked whale,[23] it might instead represent the famous beluga sturgeon due to its size (430cm in length), but fossil records suggest certain ancestors of modern dolphins and whales, such as Macrokentriodon morani (bottlenose dolphins) and Balaenoptera sibbaldina (blue whales) were presumably larger than their present descendants. From the same artworks, auks, like Brunnich's Guillemot could also have been in the sea as well, and these petroglyphs suggest marine inflow between the current Caspian Sea and the Arctic Ocean or North Sea, or the Black Sea.[26] This is supported by the existences of current endemic, oceanic species such as lagoon cockles which was genetically identified to originate in Caspian/Black Seas regions.[24]
Baku, which is the starting point of all sea routes of Azerbaijan, is the largest port of the Caspian Sea. Azerbaijan has access to the oceans along the Caspian Sea-Volga-Volga-Don Canal, and the Don-Sea of Azov. Along with the Volga-Don Canal, the Azerbaijani vessels have the opportunity to enter the world ocean through the Volga-Baltic and White Sea-Baltic canals. Moreover, oil tankers are being transported through the Caspian Sea. Baku Sea Trade Port and Caspian Shipping Company CJSC, have a big role in the sea transportation of Azerbaijan. The Caspian Sea Shipping Company CJSC, along with the transport fleet, also includes a specialized fleet and shipyards. The transport fleet consists of 51 vessels, including 20 tankers, 13 ferries, 15 universal dry cargo vessels, 2 Ro-Ro vessels, as well as 1 technical vessel and 1 floating workshop. The specialized fleet includes 210 vessels, including 20 cranes, 25 towing and supplying vehicles, 26 passenger, two pipe-laying, six fire-fighting, seven engineering-geological, two diving and 88 auxiliary vessels.[44]
The Rus' launched the first large-scale raid in 913. A fleet of 500 ships reached the southern shores of the Caspian Sea through the country of the Khazars. In order to secure a peaceful passage through the land of the Khazars, the Rus' promised the Khazars half of their spoils. They sailed down the Dnieper River into the Black Sea, then into the Sea of Azov, then up the Don River past the Khazar city of Sarkel, and then by a portage reached the Volga, which led them into the Caspian Sea.
The Aral–Caspian Depression is a lowland depression straddling Europe and Asia around the Aral Sea and Northern Caspian Sea. The most northern part is called the Caspian Depression. The desert part to the east of the Caspian Depression and Caspian is called the Turan Depression. In Azerbaijan, the Kura-Aras Lowland is part of the Aral–Caspian Depression. 
Turkic languages refer to the lake as Khazar Sea. In Turkmen, the name is Hazar deňizi, in Azeri, it is Xəzər dənizi, and in modern Turkish, it is Hazar denizi. In all these cases, the second word simply means "sea", and the first word refers to the historical Khazars who had a large empire based to the north of the Caspian Sea between the 7th and 10th centuries. An exception is Kazakh, where it is called Каспий теңізі, Kaspiy teñizi (Caspian Sea).
The Caspian Depression (, Caspian Lowland) or Pricaspian/Peri-Caspian Depression/Lowland is a low-lying flatland region encompassing the northern part of the Caspian Sea, the largest enclosed body of water on Earth. It is the larger northern part of the wider Aral-Caspian Depression around the Aral and Caspian seas.
A theory proposed by Andrey Tchepalyga of the Russian Academy of Sciences dates the flooding of the Black Sea basin to an earlier time and from a different cause. According to Tchepalyga, global warming beginning from about 16,000 BP caused the melting of the Scandinavia Ice Sheet, resulting in massive river discharge that flowed into the Caspian Sea, raising it to as much as above normal present-day levels. The Sea of Azov rose so high that it overflowed into the Caspian Sea. The rise was extremely rapid and the Caspian basin could not contain all the floodwater, which flowed from the northwest coastline of the Caspian Sea, through the Kuma-Manych Depression and Kerch Strait into the Black Sea basin. By the end of the Pleistocene this would have raised the level of the Black Sea by some below its present-day level, and flooding large areas that were formerly available for settlement or hunting. Tchepalyga suggests this may have formed the basis for legends of the great Deluge.
It had a distinct coastline in former times, but since the 1990s, with higher Caspian Sea levels, the water penetrates inland through the neck of the bay producing waterlogged marshes. Located at the mainland end of the bay, the Kaydak Inlet cuts deep into the coast extending east and then southwards. Nowadays both the bay and the inlet are filled with Caspian Sea water. Currently there are oil fields in the area.
Owing to its special colour the Dead Kultuk is the bay which appears in early maps of the Caspian Sea as 'Blue Sea' ( in maps in that language). The area was mapped by Fedor Ivanovich Soimonov during the Caspian Expedition, which surveyed the Caspian Sea from 1719 to 1727, but was not accurately described until G. S. Karelin did so in 1832.
The Murghab River and the Tejen River flow from Afghanistan but peter out in the Karakum Desert. The Atrek River is a shorter river flowing from Iran, but only reaching the Caspian Sea in time of flood. The Amudarya River flows northwestwards near the border with Uzbekistan before emptying into the remnants of the Aral Sea. Garabogazköl gulf is a large shallow lagoon that is sometimes connected to the Caspian Sea and has a much higher salinity, surpassing the far-famed hypersaline lake of the Dead Sea. 
With the exception of the Caspian coast, the climate of Turkmenistan is continental, with hot dry summers with the average July temperatures exceeding . In the Karakum Desert, summer temperatures can reach , while on the coast they are a little less hot, but it is more humid. In the winter, the north is cold and moist, with a mean January temperature of , while the south is slightly less cold and also moist, with the temperature averaging above . The daily temperature range is large. The highest precipitation is in the mountains, mostly falling in the winter and spring, while elsewhere the precipitation is low, and over most of the country, water is in short supply.
In autumn and winter, Caspian seals prey mostly on sculpins, gobies, and crustaceans while inhabiting shallow waters in the northern part of the sea. During the summer, in the southern part of the Caspian Sea, they eat herring, roach, carp, sprat, and smelt. When Caspian seals live in estuaries, they eat large amounts of the freshwater species, "Sander lucioperca". Other prey include shrimp, crab, and silversides.
The salinity of the bay is about 35%, compared to the Caspian Sea's 1.2%, and 3–4% for the bulk of the world's oceans. Because of the exceptionally high salinity, comparable to the Dead Sea, it has practically no marine vegetation. Large evaporite, mostly salt deposits accumulated at the south shore were harvested by the local population since the 1920s, but in the 1930s manual collection stopped and the industry shifted northwest to its present center near Garabogaz. From the 1950s on, ground water was pumped from levels lower than the bay itself, yielding more valuable types of salts. In 1963 construction began at Garabogaz on a modern plant for increased production of salines, all the year round and independently of natural evaporation. This plant was completed in 1973.
In March 1980, the barrier to the Caspian was blocked, due to concerns evaporation was accelerating a fall in Caspian Sea level, reducing water levels. The resulting "salt bowl" caused widespread problems of blowing salt, reportedly poisoning the soil and causing health problems for hundreds of kilometers downwind to the east. In 1984 the lake was completely dry. In June 1992, when Caspian Sea levels were rising again, the barrier was breached, allowing Caspian water to again refill Garabogazköl. The remnants of the breached dam can be seen in the satellite photo of the inlet, near the Caspian Sea entrance.
The British Caspian Flotilla was a naval force of the Royal Navy established in the Caspian Sea in 1918. It was part of the allied intervention in the Russian Civil War. The flotilla initially reported to the Rear-Admiral Commanding, Black Sea, Caspian Sea and Sea of Marmora until 1919.
The Caspian red deer ("Cervus elaphus maral"), is one of the easternmost subspecies of red deer that is native to areas between the Black Sea and Caspian Sea such as Crimea, Asia Minor, the Caucasus Mountains region bordering Europe and Asia, and along the Caspian Sea region in Iran. The Caspian red deer is sometimes referred to as maral, noble deer, or eastern red deer.
The lower part of the river flows through the Kura-Aras Lowland, which covers most of central Azerbaijan and abuts the Caspian Sea. The Kura is the third largest, after the Volga and Ural, of the rivers that flow into the Caspian. Its delta is the fourth largest among the rivers that flow into the Caspian Sea, and is divided into three main sections, or "sleeves", composed of sediment the river deposited during different periods of time. Before 1998, the river flowed all the way to the tip of the delta, where it discharged into the Caspian. In that year, the river escaped its channel and started to flow off to the west, leaving the last few kilometers abandoned. The course change is believed to be the result of a rise in the level of the Caspian Sea coupled with a major flood of the Kura.
Lake-effect or sea-effect snow occurs in other countries, near large lakes or large sea areas. In Eurasia, it occurs in the regions of the Black Sea in Georgia and Turkey, the Caspian sea in Iran, the Adriatic Sea in Italy, the North Sea, as well as the Irish Sea and the Aegean Sea, the Balearic Islands, the Baltic Sea as well as areas surrounding the Sea of Japan.
The Garabogazköl Aylagy or Kara-Bogaz-Gol (, black (or mighty) strait lake) is a shallow inundated depression in the northwestern corner of Turkmenistan. It forms a lagoon of the Caspian Sea with a surface area of about . It is separated from the Caspian Sea proper, which lies immediately to the west, by a narrow, rocky ridge having a very narrow opening in the rock through which the Caspian waters flow, cascading down into Garabogazköl, leading to the Turkmen language name of the bay, "Mighty Strait Lake". The water volume of the bay fluctuates seasonally with the Caspian Sea; at times it becomes a large bay of the Caspian Sea, while at other times its water level drops drastically.
Much praise has been directed toward the film's footage of the Caspian Sea. Rosenbaum largely credited the film's appeal to its "idyllic setting", Nield called Barnet's use of scenery, taken with the film's musical score, "continually remarkable", and French film producer has even said that the beauty of the opening scene has given him an erection. The sea's sexual resonance was on Rosenbaum's mind as well, upon a second viewing. Noting the views of Luc Moullet, who contended that eroticism is always linked together with right wing ideology, Rosenbaum countered that "By the Bluest of Seas" successfully sexualizes the left-wing ideologies of collectivism and socialism, and dubbed the Caspian Sea, "a perfect emotional metaphor" for this. Writing that the sea's "force and beauty" represents the turbulent emotions of the characters, Friel agreed that symbolic meaning can be seen the film's use of the Caspian Sea.
The Caspian Sea is the world's largest inland body of water, variously classed as the world's largest lake or a full-fledged sea. It is an endorheic basin (a basin without outflows) located between Europe and Asia, to the east of the Caucasus Mountains and to the west of the broad steppe of Central Asia. It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the west, Iran to the south, and Turkmenistan to the southeast. The Caspian Sea is home to a wide range of species and may be best known for its caviar and oil industries. Pollution from the oil industry and dams on rivers draining into the Caspian Sea have had negative effects on the organisms living in the sea.
Tyuleny Island (Russian: Тюлений) is an uninhabited island in the Caspian Sea. It is located 47 km east of the Dagestan coastline, in the Caspian Sea, near the entrance to the Kizlyar Gulf.
Differences between the three regions are dramatic. The Northern Caspian only includes the Caspian shelf,[15] and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only 5–6 metres (16–20ft). The sea noticeably drops off towards the Middle Caspian, where the average depth is 190 metres (620ft).[14] The Southern Caspian is the deepest, with oceanic depths of over 1,000 metres (3,300ft), greatly exceeding the depth of other regional seas, such as the Persian Gulf. The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively.[12] The northern portion of the Caspian Sea typically freezes in the winter, and in the coldest winters ice forms in the south as well.[16]
Iranrud Baku oil fields Caspians Ekranoplan, a ground effect plane which was developed on the Caspian Sea. Epoch of Extreme Inundations Framework Convention for the Protection of the Marine Environment of the Caspian Sea Shah Deniz gas field South Caucasus Pipeline Southern Gas Corridor Tengiz Field Trans-Caspian Gas Pipeline Trans-Caspian Oil Transport System Wildlife of Azerbaijan Wildlife of Iran Wildlife of Kazakhstan Wildlife of Russia
"Aspius" species are predominantly found in Europe and Asia in large rivers draining to the North Sea, Baltic Sea, Black Sea, Sea of Azov, and the Caspian Sea. They mostly inhabit open waters with large and medium-sized lowland rivers and large lakes.
The southern region of the depression, or the north coast of the Caspian Sea, is characterized by large development of damp sites resulting from tidal phenomena. The depression is also home to a large number of insect species, with several thousand different species likely living in the region around the Caspian Sea. Studies have shown that water pollution, mostly coming from the Volga River, poses a serious threat to the biodiversity of the Caspian Depression. Water pollution is contributed mainly by industrial, agricultural, and household discharges.