Caspian Sea
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake. It contains about 3.5 times more water, by volume, than all five of North America's Great Lakes combined. The Caspian was once part of the Tethys Ocean, but became landlocked about 5.5 million years ago due to plate tectonics. The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans.
Fedor Ivanovich Soimonov
Soimonov made the first thorough hydrographic survey of the Caspian Sea between 1719 and 1727, building up on the survey previously done by Karl Van Verden during tsar Peter the Great's drive for reform and modernization at the beginning of the 18th century. He led the Caspian Expedition that explored the coasts of the sea. As a result of the survey Soimonov drew a set of maps of the Caspian for the 'Atlas of the Caspian Sea' "(Atlas Kapiiskago Moria)" and wrote the 'Pilot of the Caspian Sea'. Published in 1731 by the Russian Academy of Sciences, these became the first comprehensive report and the first modern maps of the Caspian in history. Between 1730 and 1738 he was employed as a cartographer for the Russian Admiralty Board, which had been established in 1718 by Peter I the Great.