<P> Australia, sometimes known in technical contexts by the names Sahul, Australinea or Meganesia, to distinguish it from the Australian mainland, is a continent comprising mainland Australia, Tasmania, New Guinea, New Britain, and small neighbouring islands (such as Misool and Waigeo, just to the northeast of Maluku Islands at the edge of its continental shelf). Situated in the geographical region of Oceania, it is the smallest of the seven traditional continents in the English conception . Countries within the continent include Australia, Papua New Guinea and, partially, Indonesia . </P> <P> The continent lies on a continental shelf overlain by shallow seas which divide it into several landmasses--the Arafura Sea and Torres Strait between mainland Australia and New Guinea, and Bass Strait between mainland Australia and Tasmania . When sea levels were lower during the Pleistocene ice age, including the Last Glacial Maximum about 18,000 BC, they were connected by dry land . During the past 10,000 years, rising sea levels overflowed the lowlands and separated the continent into today's low - lying arid to semi-arid mainland and the two mountainous islands of New Guinea and Tasmania . </P> <P> New Zealand is not part of the continent of Australia, but of the separate, submerged continent of Zealandia . New Zealand and Australia are both part of the Oceanian sub-region known as Australasia, with New Guinea being in Melanesia . The term Oceania is often used to denote the region encompassing the Australian continent and various islands in the Pacific Ocean that are not included in the seven - continent model . </P> <P> Papua New Guinea, a country within the continent, is one of the most culturally diverse countries in the world and also one of the most linguistically diverse places on earth . It is also one of the most rural, as only 18 percent of its people live in urban centres . West Papua is home to an estimated 44 uncontacted tribal groups . Australia, the largest landmass in the continent, is highly urbanised, and has the world's 13th - largest economy with the second - highest human development index globally . Australia also has the world's 9th largest immigrant population . The first settlers of Australia, New Guinea, and the large islands just to the east arrived between 50,000 and 30,000 years ago . </P>

New zealand is a part of what continent