Ferries in Istanbul were historically used the primary mode of public transportation between the European and Asian halves of the Istanbul. Istanbul is the crossroads of the world joining Europe to Asia, and a sea lane between the Black Sea and the Mediterranean Sea. Just as the Roman Empire was divided into two parts by Emperor Constantine, so was the city of Constantinople; the city is divided by a sea strait. That strait, the Bosphorus, played a large role in the history and even creates a need for ferries.

Istanbul Seabuses runs a combination of all-passenger ferries and car-and-passenger ferries to ports on both sides of the Bosphorus, as far north as the Black Sea. With additional destinations around the Sea of Marmara, İDO runs the largest municipal ferry operation in the world.

Boats have sailed the waters for millennia, including thousands years of navies culminating in the fall of Constantinople to the Turks in 1453. The term Sailing to Byzantium has even entered the language, where Byzantine empire was an early city state.

Istanbul (Turkish: İstanbul) is the largest city in Turkey, forming the country's economic, cultural, and historical heart. With a population of 13.4 million, the city is at the center of the second-largest urban area in Europe after Moscow, and among the world's largest cities by population within city limits. Istanbul's vast area of 5,343 square kilometers (2,063 sq mi) is coterminous with Istanbul Province, of which the city is considered capital. Straddling the Bosphorus—one of the world's busiest waterways—in northwestern Turkey, between the Sea of Marmara and the Black Sea, Istanbul is a transcontinental city, with one third of its population living in Asia but its commercial and historical center in Europe.

Founded around 660 BC as Byzantium on the Seraglio Point, the city now known as Istanbul developed to become one of the most significant cities in history. For nearly sixteen centuries following its reestablishment as Constantinople in 330 AD, it served as the capital of four empires — the late classical Roman Empire (330–395), the Eastern Roman ("Byzantine") Empire (395–1204 and 1261–1453), the Latin Empire (1204–1261), and the Ottoman Empire (1453–1922). It was instrumental in the advancement of Christianity during Roman and Byzantine times, before the Ottomans conquered the city in 1453 and transformed it into an Islamic stronghold from which the last caliphate ruled. Although the Republic of Turkey established its capital elsewhere, in Ankara, remnants of Istanbul's previous central role still remain highly visible across the city, with palaces and imperial mosques lining its hills.