St. Petersburg is a port on the Baltic Sea
Kiel There are several notable port cities in Germany that are on or near the Baltic Sea, but Kiel is the largest and most profitable.
Gdansk in Poland
Lithunia's main port is Klaipeda, on the south eastern side of Baltic Sea
There is the Russian Enclave of Kaliningrad on rhe Baltic, and St Petersburg which is on the Gulf of Finland, a branch of the Baltic Sea
Latvia, the Republic of Latvia.
Gdańsk.
Both St Petersburg and Kaliningrad
Estonia, Latvia and Lithuania
The only major port on the Baltic Sea is the Port of Hamburg in Germany. It is one of the busiest and largest ports in Europe, serving as a significant hub for international trade and shipping. The port's strategic location allows for extensive connections to various inland transportation networks, making it vital for commerce in the region.
If you mean Tsar Peter the Great, then St Petersburg
The Latvian Socialist Soviet Republic.