Why Moscow is called “Port of Five Seas”?

Moscow is called “Port of five seas” because of the Moscow Canal. Moscow Canal (length: 128 Kms) was completed in 1937, provides connectivity to five seas: the White Sea, Baltic Sea, Caspian Sea, Sea of Azov, and the Black Sea. Its name was changed from Moscow-Volga to Moscow Canal in 1947 in honor of Moscow’s 800th anniversary. Moscow Canal System which comprises of the Canal itself, Stalin Waterworks Oka and Moscow Rivers, and Uglich and Rybinsk Reservoirs provide 65-70% of Russia’s Total Potable water.
Moscow Canal is a waterway of strategic importance to Russia. (Source Official website of Moscow canal)