Sakarya is a province and metropolitan municipality in Turkey, located on the coast of the Black Sea. Its area is 4,824 km² (1,863 sq mi), and its population is 1,080,080 (2022). The Sakarya River creates a webbing of estuaries in the province, which is in the Marmara Region. The adjacent provinces are Kocaeli to the west, Bilecik to the south, Bolu to the southeast and Düzce to the east. The capital of Sakarya is Adapazarı. Its climate is maritime in the north and humid subtropical in the south and changes by the distance to the Black Sea. Sakarya is on the Ankara-Istanbul highway and is also connected by rail. Sakarya is serviced by Istanbul's Sabiha Gökçen International Airport. The mayor of Sakarya is Yusuf Alemdar as of 2024 (AKP). The city of Sakarya, one of the most important cities in Turkey for its rapid growth and development, is also noteworthy for its natural beauties and its cultural richness. It is one of the paradise-like spots of the country with its sea, beaches, lakes, rivers, highlands, thermal springs, traditional Ottoman lifestyle districts such as Taraklı and Geyve and noteworthy historical relics that are inherited from the Byzantine and the Ottoman eras. The Turks conquered the city of Sakarya in the 13th century. There was intensive immigration from the Caucasus and the Balkans in the 18th and the 19th centuries. The last massive immigration was in 1989 from Bulgaria. The city has developed industry from being a transportation crossroads and still has inward domestic migration.