Earth's biggest lake sits twenty-seven metres below ocean level
The Caspian holds more inland water than any other body on Earth—about the area of Japan—yet its surface lies roughly twenty-seven metres under true sea level. Fed mainly by the Volga and locked without an ocean outlet, it behaves like a sea, a lake, and a climate-driven reservoir all at once.
Geographers call the Caspian the world's largest inland waterbody and often its largest lake, though people still speak of it as a full sea. It is an endorheic basin straddling Europe and Asia: east of the Caucasus, west of Central Asian steppe, south of Russia's southern plains, and north of Iran's plateau. Excluding the hypersaline Garabogazköl lagoon, its surface spans about 371,000 square kilometres with a volume near 78,200 cubic kilometres. Average salinity sits around 1.2 percent—roughly one-third of open-ocean water—and five coastal states share its shores: Kazakhstan, Russia, Azerbaijan, Iran, and Turkmenistan.
North to south it stretches about 1,200 kilometres, averaging 320 kilometres across. The Volga, Europe's longest river, pours into the shallow north; central and southern basins plunge far deeper. Southern seabed reaches 1,023 metres below sea level—the third-lowest natural non-oceanic depression after Lakes Baikal and Tanganyika. The north holds under one percent of the water and freezes in winter; the middle and south hold about a third and two-thirds of the volume. More than 130 rivers feed the basin, yet outflow is essentially evaporation alone, so Caspian levels wander independently of global oceans.
Names preserve vanished peoples: Caspi tribes noted by Strabo, Khazar labels in Turkic and Arabic, Mazandaran in Iranian usage, Hyrcanian for Greeks and Persians. The Caspian seal, Pusa caspica, lives nowhere else. Oil, caviar fame, dams, and Volga pollution have stressed the ecology; UNEP flags sewage, refining, and radioactive wastes among the burdens. Twentieth-century levels fell three metres from 1929 to 1977, then rose three metres to 1995. Projections for this century warn of further drops of roughly nine to eighteen metres—or even steeper declines—under warming and desertification.
Source: Caspian Sea
