The Caspian Sea and its Kara-Bogaz-Gol Bay play an important role in different branches of the economy of Turkmenistan. Turkmen shores of the Caspian Sea have a big potential as a national and international resort area which is developing quickly. The Caspian Sea water (after desalination) is an immense source of potable and technical water for the country, living in the desert conditions. This chapter describes the main geological, physical, chemical, biological, and climatic characteristics of this largest enclosed water body in the world. Special attention is given to the Kara-Bogaz-Gol Bay, which is located in the territory of Turkmenistan and during a century played a key role in the chemical industry of the Turkmen Soviet Republic and today in Turkmenistan. © Springer-Verlag Berlin Heidelberg 2013.