The Baltic Sea is a part of the North Atlantic Ocean and is surrounded by Denmark, Sweden, Finland, Russia, the Baltic states, Poland and Germany. The Baltic Sea can be divided into many smaller regions, including the Gulf of Finland, the Bay of Bothnia and the Bay of Gdańsk. It is one of the largest brackish water areas in the world and has a surface area of around 377,000 km2. The further away from the White Sea and German Bight, the less saline the water becomes. It creates a fascinating environment where freshwater species live side by side with marine species.