Erdek is a municipality and district of Balıkesir Province, Turkey. Its area is 307 km, and its population is 31,902. Located on the Kapıdağ Penins…Erdek is a municipality and district of Balıkesir Province, Turkey. Its area is 307 km, and its population is 31,902. Located on the Kapıdağ Peninsula, on the north coast of the Gulf of Erdek at the south of the Sea of Marmara, Erdek is a popular domestic holiday destination with several hotels dating back to the 1960s. The surrounding area has a rugged geology and topography with evergreen wooded areas and large olive groves. It is dominated by Mt Dindymus. Erdek district also included the islands of Koyun and Paşalimanı.