Pemba Island, the second of two large islands, is located to the North of its sister island, Unguja (the main island, referred to as "Zanzibar"). The semi-autonomous country of Zanzibar [Map] is part of the United Republic of Tanzania is located in East Africa between 25–50 km (15–30 mi) off the coast of the mainland. It consists of the Zanzibar Archipelago in the Indian Ocean with two large islands and numerous islets.