Batam refers to both an island, municipality (an Indonesian kotamadya), the largest city in the Riau Islands Province of Indonesia, across the Strait of Singapore, the third-largest city in Sumatra region after Medan and Palembang, and the eighth-largest city in Indonesia after Jakarta Raya, Surabaya, Bandung, Medan, Semarang, Makassar, and Palembang.