Dardanelles

The Dardanelles , also known from Classical Antiquity as the Hellespont, is a narrow, natural strait and internationally significant waterway in northwestern Turkey that forms part of the continental boundary between Europe and Asia, and separates Asian Turkey from European Turkey. One of the world's narrowest straits used for international navigation, the Dardanelles connects the Sea of Marmara with the Aegean and Mediterranean Seas, while also allowing passage to the Black Sea by extension via the Bosphorus. The Dardanelles is 61 kilometres long, and 1.2 to 6 kilometres wide, averaging 55 metres deep with a maximum depth of 103 metres at its narrowest point abreast the city of Çanakkale. Most of the northern shores of the strait along the Gallipoli Peninsula are sparsely settled, while the southern shores along the Troad Peninsula are inhabited by the city of Çanakkale's urban population of 110,000.

Wikipedia