A sea without an outlet
The Caspian is the largest enclosed body of water in the world. Whether it is a sea or a lake is a long-standing question, and the answer has real legal consequences, as discussed below. It is salty, though less so than the oceans, and its surface lies below the level of the world ocean, with the level shifting over time. It has no natural connection to the ocean, so any vessel on it must have been built there or brought in by river or canal. That isolation produced a distinct maritime world, with its ports, rivals and trade routes unconnected to open-ocean seafaring.
The north is shallow and freezes in winter, while the south is deep. Winds can be strong and sudden, and the shallow northern basin has long challenged larger vessels. Major ports have included Astrakhan, at the mouth of the Volga, Derbent and Baku on the western shore, and Anzali (formerly Pahlavi) on the Iranian coast.
Early trade and the Volga
Caspian coasts have been inhabited and traded across for millennia, but the written record of shipping is thin before the medieval period. The Volga, which flows into the Caspian from the north, made the sea one end of a major riverine corridor. In the early Middle Ages, towns such as Itil, the capital of the Khazars, and the Volga Bulgars’ trading centres controlled routes between the Caspian, the Islamic world and northern Europe. Scandinavian and Slavic traders, often called the Rus, travelled down the rivers and sometimes across the Caspian, as the wider Viking-age river routes show, and Arabic writers of the tenth century recorded Rus merchants and, reportedly, raids on Caspian shores. Silver coins minted in Central Asia and the Middle East were carried north along the same routes.
Vessels on the sea were generally small and locally built. Medieval and early modern accounts mention sewn and nailed craft, and in the northern part of the sea, flat-bottomed boats suited to shallow water. Exact types are poorly recorded and should not be asserted with confidence.
Russia and Persia
Russia’s expansion into the Volga basin under Ivan IV brought the conquest of Kazan in 1552 and Astrakhan in 1556, giving Russia control of the river to its mouth. Over the following centuries the Caspian became a stage for Russian-Persian rivalry. Peter the Great led a campaign against Safavid Persia in 1722–1723 that was aided by a Russian flotilla, and the Caspian Flotilla dates from this era. Russia lost most of the territory it gained in the following decade, but by the early nineteenth century it was again dominant. Under the Treaty of Gulistan (1813), and confirmed by the Treaty of Turkmenchay (1828), Russia secured the right to keep warships on the Caspian, and Persia lost it. For much of the nineteenth century, then, the sea was effectively a Russian naval preserve.
Oil, steam and the first tankers
The Absheron Peninsula, where Baku lies, has natural oil and gas seepages that were known for centuries. In the second half of the nineteenth century the region became one of the world’s major oil-producing centres. Shipping the oil by water was important: the Nobel brothers’ firm commissioned a steamer, the Zoroaster, in 1878, and it is generally regarded as one of the earliest purpose-built oil tankers. Oil from Baku was carried across the Caspian to Astrakhan and then up the Volga in barges, and later by rail to the Black Sea. The Caspian thus played a part in the earliest history of the oil tankers that later dominated world trade.
Steamers also carried passengers and general cargo, and in the Soviet period the Caspian was linked to wider waterways. The Volga-Don Canal, opened in 1952, connects the Volga with the Don and thus with the Black Sea, so that small seagoing and river-sea vessels can pass in principle. This is a good example of how ship canal locks and cuttings could change the position of an enclosed sea.
Sturgeon and caviar
The Caspian is the home of most of the world’s wild sturgeon species, including the beluga, and their roe, caviar, has been a prized product for centuries. Fisheries were run from the Volga delta, the Iranian coast and other shores. In the nineteenth century, Russian business interests operated fishing concessions on the Persian shore under agreements with the Persian government, a point of friction. Overfishing, dam construction on rivers where sturgeon spawn, pollution and poaching later caused sharp declines, and international rules since the late twentieth century have restricted trade in wild caviar. Fish stocks and fishing practices remain a matter of ongoing study.
The sea after the Soviet Union
After the Soviet Union broke up in 1991, the Caspian had five coastal states instead of two: Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. Whether the Caspian was a sea, governed by the law of the sea, or a lake, to be shared, was disputed for years because it affected seabed resources and shipping rights. A convention signed in 2018 at Aktau set out a special legal status for the sea, though some questions, especially on the seabed, were left for further agreement. Today oil, gas, ferries and the Volga trade remain central, and Baku, Aktau, Turkmenbashi, Astrakhan and Makhachkala are among the main ports.