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.
Caspian tiger
Its former distribution can be approximated by examining the distribution of ungulates in the region. Wild boar was the numerically dominant ungulate occurring in forested habitats, along watercourses, in reed beds and in thickets of the Caspian and Aral Seas. Where watercourses penetrated deep into desert areas, suitable wild pig and tiger habitat was often linear, only a few kilometers wide at most. Red and roe deer occurred in forests around the Black Sea to the western side and around the southern side of the Caspian Sea in a narrow belt of forest cover. Roe deer occurred in forested areas south of Lake Balkash. Bactrian deer occurred in the narrow belt of forest habitat on the southern border of the Aral Sea, and southward along the Syr-Darya and Amu-Darya rivers.