Chokepoints explained
Bosphorus and the Turkish Straits
The Bosphorus runs through Istanbul, linking the Black Sea to the Sea of Marmara. With the Dardanelles it forms the Turkish Straits, the Black Sea's only sea route to the Mediterranean.
Grain, oil and other exports from Ukraine, Russia, Romania, Bulgaria and Georgia must pass through the straits to reach world markets.
Passage is governed by the Montreux Convention of 1936, which gives Türkiye powers over warship transits in wartime. Chokepoint has tracked drone attacks on merchant ships in the western Black Sea.
Countries around the Turkish Straits: this week's threat scores
Recent Chokepoint coverage
Frequently asked questions
Is Black Sea shipping safe?
Black Sea shipping carries war risk because of long range strikes in the Russia and Ukraine war. Ukraine and Turkey are working on a limited Black Sea ceasefire to protect grain exports.
What is the Bosphorus and the Turkish Straits?
The Bosphorus runs through Istanbul, linking the Black Sea to the Sea of Marmara. With the Dardanelles it forms the Turkish Straits, the Black Sea's only sea route to the Mediterranean.
Why does the Bosphorus and the Turkish Straits matter for business?
Passage is governed by the Montreux Convention of 1936, which gives Türkiye powers over warship transits in wartime. Chokepoint has tracked drone attacks on merchant ships in the western Black Sea.
Published by Zed Three. Last updated Nov 2, 2026.
Custom reports
Need a deeper read on the Turkish Straits?
Zed Three builds custom threat and risk reports around your people, suppliers and routes.
Free weekday briefing
Get Chokepoint free
The five stories that move markets, supply chains and deals, each with the so what worked out. Five minutes, every weekday morning.