Brisbane is the capital and largest city of the state of Queensland and the third-most populous city in Australia and Oceania, with a population over 2.7 million. Brisbane lies at the centre of South East Queensland, an urban agglomeration with a population of approximately 4 million which includes several other regional centres and cities. The central business district is situated within a peninsula of the Brisbane River about 15 km (9 mi) from its mouth at Moreton Bay. Brisbane is located in the hilly floodplain of the Brisbane River Valley between Moreton Island and the Taylor and D'Aguilar mountain ranges. It sprawls across several local government areas, most centrally the City of Brisbane. The demonym of Brisbane is Brisbanite.