This book presents the geological evolution of the Baltic Sea area since its inception, i.e., from the Late Glacial to the present day. The geological history of all evolutionary stages of the Baltic Sea is discussed in detail, from the Baltic Ice Lake, through the Yoldia Sea, Ancylus Lake, Littorina Sea and Lymnaea Sea, to the Mya Sea as the modern stage of the Baltic Sea development. The author presents palaeoecological and palaeosedimentological analyses of various evolutionary stages of the Baltic Sea. Detailed paleogeographic maps of the development of the Littorina Sea, Lymnaea Sea and Mya Sea are displayed, with particular focus on the Polish Baltic Sea area. Moreover, characteristic geological cross-sections and synthetic stratigraphic profiles representing individual areas of the Polish Baltic Sea coast are also shown. Each transgressive cycle of the various developmental stages of the Baltic Sea is characterized in terms of the average rate of marine transgression, the fluctuation of Baltic levels and the average rate of marine abrasion of the then cliff and spit shores, as well as the evolutionary changes of the area. In addition, the lithostratigraphic characteristics of the various marine sediment complexes and dune sediments (brown dune spits, yellow dune spits, light yellow-grey dune spits and grey dune spits) are also presented. Individual chapters address key aspects of: • Litho-stratigraphical analysis of the Baltic Ice Lake deposits. • Litho-stratigraphical analysis of the Yoldia Sea deposits. • Litho-stratigraphical analysis of the Ancylus Lake deposits. • Paleogeography, litho-stratigraphy and transgressive cycles of the Littorina Sea. • Paleogeography, litho-stratigraphy and transgressive cycles of the Lymnaea Sea. • Paleogeography, litho-stratigraphy and transgressive cycles of the Mya Sea. • New stratigraphic division of the southern Baltic deposits along the Polish coast. The book will be useful for students and scientists of marine geology, oceanography, geography and environmental engineering. It will also be of practical use for all specialists dealing with marine basins and coastal zones, including marine geologists, coastal geologists and geomorphologists, geographers, as well as engineering geologists, geotechnicians and civil engineers. The book is generally related to the discipline of marine geology, and deals directly with the Baltic Sea basin.