Bosporus in the context of "Battle of Chrysopolis"

The Mediterranean Sea (/ˌmɛdɪtəˈreɪniən/ MED-ih-tə-RAY-nee-ən) is an intercontinental sea situated between Europe, Asia, and Africa. It is surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Europe, and on the south by North Africa. To its west it is connected to the Atlantic Ocean via the Strait of Gibraltar that separates the Iberian Peninsula in Europe from Morocco in Africa by only 14 km (9 mi); additionally, it is connected to the Black Sea through the Bosporus strait that intersects Turkey in the northeast and the Red Sea via the Suez Canal in the southeast.

The Mediterranean Sea covers an area of about 2,500,000 km (970,000 sq mi), representing 0.7% of the global ocean surface; it includes fifteen marginal seas, including the Aegean, Adriatic, Tyrrhenian, and Marmara. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago.

The Black Sea is a marginal sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is supplied by major rivers, principally the Danube, Dnieper and Dniester. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe.

The Black Sea, not including the Sea of Azov, covers 436,400 km (168,500 sq mi), has a maximum depth of 2,212 m (7,257 ft), and a volume of 547,000 km (131,000 cu mi).Most of its coasts ascend rapidly.These rises are the Pontic Mountains to the south, bar the southwest-facing peninsulas, the Caucasus Mountains to the east, and the Crimean Mountains to the mid-north.In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end of the Balkan Mountains; and the Dobruja Plateau considerably farther north. The longest east–west extent is about 1,175 km (730 mi). Important cities along the coast include (clockwise from the Bosporus) the northern suburbs of Istanbul, Burgas, Varna, Constanța, Odesa, Yalta, Kerch, Yevpatoria, Sevastopol, Novorossiysk, Sochi, Poti, Batumi, Rize, Trabzon, Ordu, Simferopol, Samsun and Zonguldak.

Anatolia (Turkish: Anadolu), also known as Asia Minor, is a peninsula in West Asia that makes up the majority of the land area of Turkey. It is the westernmost protrusion of Asia and is geographically bounded by the Mediterranean Sea to the south, the Aegean Sea to the west, the Turkish Straits to the northwest, and the Black Sea to the north. The eastern and southeastern limits have been expanded either to the entirety of Asiatic Turkey or to an imprecise line from the Black Sea to the Gulf of Alexandretta. Topographically, the Sea of Marmara connects the Black Sea with the Aegean Sea through the Bosporus and the Dardanelles, and separates Anatolia from Thrace in Southeast Europe.

During the Neolithic, Anatolia was an early center for the development of farming after it originated in the adjacent Fertile Crescent. Beginning around 9,000 years ago, there was a major migration of Anatolian neolithic farmers into Europe, with their descendants coming to dominate the continent as far west as the Iberian Peninsula and the British Isles.

Constantinople (see other names) was a historical city located on the Bosporus that served as the capital of the Roman (including its eastern continuation), Latin, and Ottoman empires between its consecration in 330 and the formal abolishment of the Ottoman sultanate in 1922. Initially, as New Rome, Constantinople was founded in 324 during the reign of Constantine the Great on the site of the existing settlement of Byzantium and in 330 became the capital of the Roman Empire. Following the collapse of the Western Roman Empire in the late 5th century, Constantinople remained the capital of the Eastern Roman Empire (also known as the Byzantine Empire; 330–1204 and 1261–1453), the Latin Empire (1204–1261), and the Ottoman Empire (1453–1922). In the aftermath of the Turkish War of Independence, the Turkish capital moved to Ankara. Although the city had been known as Istanbul since 1453, it was officially renamed Istanbul on 28 March 1930. As of October 2025, it is the most populous city in Europe, with a population of more than 16 million residents, straddling the Bosporus Strait and lying in both Europe and Asia, and is the financial center of Turkey.

In 324, following the reunification of the Eastern and Western Roman Empires, the ancient city of Byzantium was selected to serve as the new capital of the Roman Empire, and the city was renamed Nova Roma, or 'New Rome', by Emperor Constantine the Great. On 11 May 330, it was renamed Constantinople and dedicated to Constantine. Shortly afterward, in 474 AD, the Great Fire of Constantinople erupted and consequently devastated the region. Constantinople is generally considered to be the center and the "cradle of Orthodox Christian civilization." From the mid-5th century to the early 13th century, Constantinople was the largest and wealthiest city in Europe. The city became famous for its architectural masterpieces, such as Hagia Sophia, the cathedral of the Eastern Orthodox Church, which served as the seat of the Ecumenical Patriarchate; the sacred Imperial Palace, where the emperors lived; the Hippodrome; the Golden Gate of the Land Walls; and opulent aristocratic palaces. The University of Constantinople was founded in the 5th century and contained artistic and literary treasures before it was sacked in 1204 and 1453, including its vast Imperial Library. which contained more than 100,000 volumes. The city was the home of the Ecumenical Patriarch of Constantinople and guardian of Christendom's holiest relics, such as the Crown of Thorns and the True Cross.

East Thrace or Eastern Thrace, also known as Turkish Thrace or European Turkey, is the part of Turkey that is geographically in Southeast Europe. Turkish Thrace accounts for 3.03% of Turkey's land area and 15% of its population. The largest city is Istanbul, which straddles the Bosporus between Europe and Asia. East Thrace is of historic importance as it is next to a major sea trade corridor and constitutes what remains of the once-vast Ottoman region of Rumelia. It is currently also of specific geostrategic importance because the sea corridor, which includes two narrow straits, provides access to the Mediterranean Sea from the Black Sea for the navies of five countries: Russia, Ukraine, Romania, Bulgaria, and Georgia. The region also serves as a future connector of existing Turkish, Bulgarian, and Greek high-speed rail networks.Due to the guest worker agreement with Turkey and Germany, some Turks in Germany originally come from Eastern Thrace, mostly from the Kırklareli Province.

The Turkish Straits (Turkish: Türk Boğazları) are two internationally significant waterways in northwestern Turkey. The Straits create a series of international passages that connect the Aegean and Mediterranean seas to the Black Sea. They consist of the Dardanelles and the Bosphorus. The straits are on opposite ends of the Sea of Marmara. The straits and the Sea of Marmara are part of the sovereign sea territory of Turkey and are treated as Turkish internal waters.

Located in the western part of the landmass of Eurasia, the Straits are conventionally considered the boundary between the continents of Europe and Asia, as well as the dividing line between European Turkey and Asian Turkey. Owing to their strategic importance in international commerce, politics, and warfare, the Straits have played a significant role in European and world history. Since 1936, they have been governed in accordance with the Montreux Convention.

The Sea of Marmara, also known as the Sea of Marmora or the Marmara Sea, is a small inland sea entirely within the borders of Turkey. It links the Black Sea and the Aegean Sea via the Bosporus and Dardanelles straits, separating Turkey's European and Asian sides. It has an area of 11,350 km (4,380 sq mi), and its dimensions are 280 km × 80 km (174 mi × 50 mi). Its greatest depth is 1,370 m (4,490 ft).

The Dardanelles (/ˌdɑːrdəˈnɛlz/ DAR-də-NELZ; Turkish: Çanakkale Boğazı, lit. 'Strait of Çanakkale'; Greek: Δαρδανέλλια, romanized: Dardanéllia), also known as the Strait of Gallipoli (after the Gallipoli peninsula) and in classical antiquity as the Hellespont (/ˈhɛlɪspɒnt/ HEL-isp-ont; Classical Greek: Ἑλλήσποντος, romanized: Hellḗspontos, lit. 'Sea of Helle'), is a narrow, natural strait and internationally significant waterway in northwestern Turkey that forms part of the continental boundary between Asia and Europe and separates Asian Turkey from European Turkey. Together with the Bosporus, the Dardanelles forms the Turkish Straits.

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 Bosporus. The Dardanelles is 61 kilometres (38 mi) long and 1.2 to 6 kilometres (0.75 to 3.73 mi) wide. It has an average depth of 55 metres (180 ft) with a maximum depth of 103 metres (338 ft) at its narrowest point abreast the city of Çanakkale. The first fixed crossing across the Dardanelles opened in 2022 with the completion of the 1915 Çanakkale Bridge.