Which strategic waterway connects the Black Sea with the Sea of Marmara, passing through Istanbul?

The Bosphorus Strait is a pivotal waterway that serves as the only natural passage connecting the Black Sea to the Sea of Marmara. This strait runs directly through Istanbul, which is a city that straddles two continents, Europe and Asia. Its geographical significance is immense, as it not only facilitates maritime navigation but also serves as a critical point of cultural and economic exchange between the eastern and western parts of the world.

The Bosphorus is particularly important for the countries bordering the Black Sea, as it is their main outlet to international waters. Control over this strait has historically been a strategic asset, impacting trade and military routes. This is what makes the Bosphorus a crucial maritime corridor and the correct answer to the question.

Additionally, the other waterways mentioned are important in their own contexts but do not connect the Black Sea to the Sea of Marmara or pass specifically through Istanbul. The Strait of Gibraltar is located between Spain and Morocco, the Strait of Hormuz is between Iran and Oman, and the Dardanelles Strait connects the Aegean Sea to the Sea of Marmara but does not directly link to the Black Sea.