The Gulf of Finland is the easternmost arm of the Baltic Sea, extending between Finland to the north and Estonia to the south, reaching east to Saint Petersburg where the River Neva drains into it.
Major cities ringing the gulf include Helsinki, Tallinn and Saint Petersburg — Russia’s second-largest city. The eastern portions of the gulf belong to Russia and host some of the country’s most important oil harbours, including Primorsk, making the gulf a seaway of considerable strategic importance. The gulf is relatively shallow, and many of the environmental problems affecting the wider Baltic Sea — nutrient pollution, algal blooms, declining oxygen levels — are at their most acute here. Engineers have proposed an undersea tunnel linking Helsinki and Tallinn beneath the gulf, though the project remains unrealised.
