Unguja (also referred to as Zanzibar) is the largest and most populated island of the archipelago. Unguja is a hilly island, about 85 kilometers long (north-south) and 30 kilometers wide (east-west) at its widest, with an overall area of about 1,666 square kilometers and separated from Tanzania mainland by the Zanzibar Channel. Surrounded by a number of small islets, with only two of them, Tumbatu and Uzi, being inhabited, the archipelagos population including Pemba island is in total just over 1 million.