Caspian Sea the east often changed course to empty into the Caspian through a now-desiccated riverbed called the Uzboy River, as did the Syr Darya farther north. The Caspian also has several small islands; they are primarily located in the north and have a collective land area of roughly . Adjacent to the North Caspian is the Caspian Depression, a low-lying region below sea level. The Central Asian steppes stretch across the northeast coast, while the Caucasus mountains hug the western shore. The biomes to both the north and east are characterized by cold, continental deserts. Conversely, the climate to the southwest
Caspian Sea kind of oil which is white and very precious [i.e., petroleum]." In the 18th century, during the rule of Peter I the Great, Fedor I. Soimonov, hydrographer and pioneering explorer of the Caspian Sea charted the until then little known body of water. Soimonov drew a set of four maps and wrote "Pilot of the Caspian Sea", the first report and modern maps of the Caspian, that were published in 1720 by the Russian Academy of Sciences. Today, oil and gas platforms abound along the edges of the sea. Countries on the Caspian region, such as Azerbaijan, Kazakhstan and Turkmenistan,