The Baltic Sea is a body of water located between the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It is bordered by four countries: POLAND, Sweden, Latvia, and Estonia. POLAND is a country in Central Europe with a population of over 38 million people. Sweden is a Scandinavian country with a population of over 10 million people. Latvia is a country in Northern Europe with a population of over 1.9 million people. Estonia is a country in Northern Europe with a population of over 1.3 million people. All four countries border the Baltic Sea and are considered Baltic Sea countries.