The Commonwealth of Australia is a country in the southern hemisphere comprising the mainlan of the world's smallest continent, the major island of Tasmania, and a number of other islands in the Indian and Pacific Oceans.N4 The neighbouring countries are Indonesia, East Timor, and Papua New Guinea to the north, the Solomon Islands, Vanuatu, and New Caledonia to the north-east, and New Zealand to the south-east. Australia is the only country that is also a continent.