The Commonwealth of Australia is a country in the southern hemisphere comprising the mainland of the world's smallest continent, the major island of Tasmania, and numerous other islands in the Indian and Pacific Oceans.Note4 The neighbouring countries are Indonesia, East Timor, and Papua New Guinea to the north, the Solomon Islands, Vanuatu, and New Caledonia to the northeast, and New Zealand to the southeast. Australia is the only continent occupied by a single country.