13/08/2026
Black Sea —
1. Location & type: World’s largest inland (landlocked) sea, between SE Europe and Asia Minor; classified as a marginal sea of the Atlantic Ocean. Ancient Greeks called it “Pontus Euxinus.”
2. Bordering countries (6): Turkey, Bulgaria, Romania, Ukraine, Russia, Georgia.
3. Connectivity: Joins the Mediterranean via Bosphorus Strait → Sea of Marmara → Dardanelles Strait; joins the Sea of Azov via the Kerch Strait.
4. Montreux Convention (1936): Governs naval vessel passage through the Turkish Straits — a favourite for UPSC IR questions, since it shapes Russia’s naval access to the Mediterranean.
5. Size: Area ≈ 4.36 lakh sq km; maximum depth ≈ 2,212 m.
6. Low salinity: About half of open-ocean salinity (~18‰ vs ~35‰), due to heavy river inflow and restricted exchange with the Mediterranean.
7. Rivers draining into it: Danube (biggest contributor), Dnieper, Dniester, Don (via Sea of Azov), Kuban, Rioni.
8. World’s largest meromictic basin: Water layers don’t mix — oxygen-rich surface, but an anoxic, hydrogen-sulphide-rich deep zone below ~150–200 m where little marine life survives.
9. Major ports: Constanta (Romania, largest); Odesa & Chornomorsk (Ukraine); Novorossiysk & Sochi (Russia); Istanbul & Trabzon (Turkey); Varna (Bulgaria); Batumi (Georgia).
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