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Sakarya (Turkish: Sakarya ili) is a province in Turkey, located on the coast of Black Sea. The Sakarya River creates a webbing of estuaries in the province. Sakarya is located in the Marmara Region. Its 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. The climate is maritime in the north and humid subtropical in the south, changing with proximity to the Black Sea.

Sakarya is situated on the Ankara-Istanbul Highway. It is connected through both road and rail. Sakarya is serviced by Istanbul's Sabiha Gökçen International Airport. The current mayor of Sakarya is Ekrem Yüce as of 2019. (AKP). The city of Sakarya, one of the most important cities in Turkey for its rapid growth and development, is also attention worthy for its natural beauties and cultural richness. It is one of the paradise-like spots of the country with its sea, beaches, lakes, rivers, highlands, thermal springs along with traditional Ottoman lifestyle districts such as Taraklı and Geyve, and historical relics inherited from the Byzantine and Ottoman eras that are worth witnessing.

The Turks conquered the city of Sakarya in the 13th century. There was intensive immigration from Caucasia and the Balkans in the 18th and 19th centuries. The last massive immigration was in 1989. Thanks to the developing industry and being at a transportation crossroads, the city still receives domestic migration today. Sakarya is notable in the Marmara Region.

The city of Sakarya is surrounded with the city of Düzce in the East, Bolu in the South East, Bilecik in the South, Kocaeli in the West and the Black Sea in the North. The city of Sakarya has 16 districts which are; Adapazarı, Akyazı, Arifiye, Erenler, Ferizli, Geyve, Hendek, Karapürçek, Karasu, Kaynarca, Kocaali, Pamukova, Sapanca, Serdivan, Söğütlü and Taraklı.