To fully understand what the currents are like in the Baltic Sea, you must first understand the numerous waterways that are in and around the Baltic Sea. The Shagerrak, which borders the North Sea, and the Kattegat, bordering Denmark, make up the westernmost areas of the Baltic Sea. The Baltic Sea is also made up of three gulfs that contribute significantly to the water current: the Gulf of Riga, the Gulf of Finland and the Gulf of Bothnia. The Gulf of Riga is located on the Baltic Sea's eastern edge, the Gulf of Finland is located on its northeastern edge and the Gulf of Bothnia is home to the northernmost parts of the Baltic Sea.
The three gulfs located in the Baltic Sea have an impact on the Baltic's water currents. The Gulf of Riga has its own counter-clockwise water current; the Gulf of Finland has a similar counter-clockwise water current and the current flows directly into the Gulf of Bothnia. The Gulf of Bothnia's water current flows north until its northernmost point, where the current has a counter-clockwise rotation until the water flows back south into the Baltic Sea.
The main currents in the Baltic Sea can be divided by the Swedish island of Gotland. The current flows north along the coasts of Poland, Lithuania and Latvia, all south and east of Gotland. Directly east and west of Gotland, however, the currents flow mainly south towards the Polish island of Bornholm and the Bornholm Basin. The Baltic Sea currents move rather slowly, as it takes between 25 to 35 years for the waters in the Baltic Sea to be replenished from the waters of the North Sea and Atlantic.
The Shagerrak and Kattegat waterways lie on the westernmost end of the Baltic Sea and connect the Baltic to the North Sea. The Shagerrak is located off the coasts of Norway and Denmark, and links directly to the North Sea, while the Kattegat borders the coasts of Sweden, Denmark and Germany and is made up of the Oresund, Great Belt and Little Belt. The Baltic Sea currents flow east to west into the Kattegat through the Danish islands, and the currents push north through the Kattegat and into the Shagerrak. The currents in the Shagerrak flow east along the Danish coast and loop back west toward the North Sea along the Norwegian coast.
