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.
Trans-Caspian railway
Construction began in 1879 of a narrow-gauge railway to Gyzylarbat in connection with the Russian conquest of Transcaspia under General Mikhail Skobelev. It was rapidly altered to the standard Russian gauge of five feet, and construction through to Ashkabad and Merv (modern Mary) was completed under General Michael Nicolaivitch Annenkoff in 1886. Originally the line began from on the Caspian Sea, but the terminus was later shifted north to the harbour at Krasnovodsk. The Railway reached Samarkand via Bukhara in 1888, where it halted for ten years until extended to Tashkent and Andijan in 1898. The permanent bridge over the Oxus (Amu-Darya) was not completed until 1901, and until then trains ran over a rickety wooden construction that was often damaged by floods. As early as 1905, there was a train ferry across the Caspian Sea from Krasnovodsk to Baku in Azerbaijan. The Tashkent Railway connecting the Transcaspian Military Railway with the network of other Russian and European railways was completed in 1906.