Liepāja
Liepāja is a now-abandoned ice-free Latvian harbor on the Baltic Sea. It has 16 terminals to ensure the cargo exchange between East and West Europe. It is the third largest port in the country, but it once had a different purpose. The harbor housed 16 subs and a nuclear deposit in the Karosta neighborhood. It was created as a naval base for Tsar Alexander III before it was turned into the Soviet Baltic Fleet base.

Liepāja
Saint Nazaire Submarine Base
In WW2, the Nazis created a number of large submarine bases all over France. Saint Nazaire was the biggest of the submarine bases created by the Third Reich in Vichy France. They overtook the harbor after they arrived in June 1940 and used it for their submarines. The allies later destroyed the town but left this base intact. It is now a cultural site full of bars, museums, and a French submarine. Interesting!

Saint Nazaire Submarine Base