BAKU, July 25 — The Caspian Sea, the world’s largest inland body of water, is a paradox: a vast endorheic basin that straddles Europe and Asia, celebrated for its caviar and oil yet threatened by pollution and a slow-motion ecocide. Stretching 1,200 kilometres from north to south, with an average width of 320 kilometres, it covers 371,000 square kilometres — an area roughly the size of Japan — and holds 78,200 cubic kilometres of water. Its salinity, about 1.2 percent, is roughly one-third that of average seawater.
The name itself reaches into antiquity, derived from the ancient Iranic Caspi people who once inhabited its shores.
A Sea of Extremes
The Caspian’s geography is defined by sharp contrasts. Its shallow northern end receives the main freshwater inflow from Europe’s longest river, the Volga. To the south, two deep basins create horizontal differences in temperature, salinity, and ecology.
The seabed plunges to 1,023 metres below sea level, making it the third-lowest natural non-oceanic depression on Earth, after Lake Baikal and Lake Tanganyika. The surface itself sits about 27 metres below global sea level.
Excluding the highly saline lagoon of Garabogazköl to the east, the sea’s gross coverage is 386,400 square kilometres — five times the size of Lake Superior. This inland sea is home to a wide range of animal species and has long been famous for its caviar and oil industries.
Environmental Pressure
Against this backdrop of grandeur, the Caspian faces mounting environmental damage. Pollution from the oil industry and dams on rivers that drain into the sea have already harmed its ecology. The outlook is stark: it is predicted that during the 21st century, the depth of the sea will decrease by 9 to 18 metres due to global warming and the process of desertification, leading to an ecocide.
The Volga, which supplies the bulk of the sea’s freshwater, is itself subject to upstream dam construction and diversion. The wider picture is one of a shrinking, increasingly saline water body, with profound consequences for the region’s biodiversity, fisheries, and the communities that depend on them.
Legal Ambiguity, Strategic Stakes
The legal classification of the Caspian Sea — whether it is a sea or a lake — carries strategic implications for the five bordering nations: Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the southwest, Iran to the south, and Turkmenistan to the southeast. If treated as a sea, international maritime law would apply, granting each coastal state exclusive economic zones and rights to the seabed beyond a continental shelf.
If classified as a lake, the body would be subject to joint sovereignty, requiring consensus on resource extraction and military access. In the corridors of the five capitals, this ambiguity has long stalled negotiations over oil and gas fields, pipelines, and naval deployments.
What is at stake is nothing less than the control of the Caspian’s energy wealth and the future of its fragile ecosystem. As the water level falls and the pressures mount, the nations that share this unique inland sea have yet to settle the fundamental question of what it really is — and who owns what lies beneath its surface.
