Which sea is bordered by Poland, Sweden, Finland, and the Baltic states?

The sea bordered by Poland, Sweden, Finland, and the Baltic states is the Baltic Sea.

The Baltic is a semi-enclosed arm of the Atlantic Ocean in northern Europe. Its coastline also includes Denmark, Germany, Russia, Estonia, Latvia, and Lithuania. The Baltic states specifically are Estonia, Latvia, and Lithuania, all located along its eastern and southeastern shores.

Because the Baltic has limited exchange with the open ocean through the Danish Straits, river runoff and relatively low evaporation make it the world's largest brackish-water sea. Its major subdivisions include the Gulf of Bothnia, Gulf of Finland, Gulf of Riga, and Bay of Gdańsk.

A common mix-up is the North Sea, which lies west of Denmark and connects to the Baltic through the Skagerrak and Kattegat. The White Sea is also connected to the Baltic by canal, but it is a separate Arctic sea in northwestern Russia.