Tasmania in the context of "Mainland Australia"

The continent of Australia, sometimes known in technical contexts as Sahul (/səˈhuːl/), Australia-New Guinea, Australinea, or Meganesia to distinguish it from the country of Australia, is located within the Southern and Eastern hemispheres, near the Maritime Southeast Asia. The continent includes mainland Australia, Tasmania, the island of New Guinea (Papua New Guinea and Western New Guinea), the Aru Islands, the Ashmore and Cartier Islands, most of the Coral Sea Islands, and some other nearby islands. Situated in the geographical region of Oceania, more specifically in the subregion of Australasia, Australia is the smallest of the seven traditional continents.

The continent includes 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 into the combined landmass of Sahul. The name "Sahul" derives from the Sahul Shelf, which is a part of the continental shelf of the Australian continent. During the past 18,000 to 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. With a total land area of 8.56 million square kilometres (3,310,000 sq mi), the Australian continent is the smallest, lowest, flattest, and second-driest continent (after Antarctica) on Earth. As the country of Australia is mostly on a single landmass, and comprises most of the continent, it is sometimes informally referred to as an island continent, surrounded by oceans.

Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It has a total area of 7,688,287 km (2,968,464 sq mi), making it the sixth-largest country in the world and the largest in Oceania. Australia is the world's flattest and driest inhabited continent. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates including deserts in the interior and tropical rainforests along the coast.

The ancestors of Aboriginal Australians began arriving from Southeast Asia 50,000 to 65,000 years ago, during the Last Glacial Period. By the time of British settlement, Aboriginal Australians spoke more than 250 distinct languages and had one of the oldest living cultures in the world. Australia's written history commenced with Dutch exploration of most of the coastline in the 17th century. British colonisation began in 1788 with the establishment of the penal colony of New South Wales. By the mid-19th century, most of the continent had been explored by European settlers and five additional self-governing British colonies were established, each gaining responsible government by 1890. The colonies federated in 1901, forming the Commonwealth of Australia. This continued a process of increasing autonomy from the United Kingdom, highlighted by the Statute of Westminster Adoption Act 1942, and culminating in the Australia Acts of 1986.

An isthmus (/ˈɪs(θ)məs/ ISS-məs, ISTH-məs; pl.: isthmuses or isthmi /-maɪ/ -⁠my; from Ancient Greek ἰσθμός isthmós 'neck') is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmus, a narrow stretch of sea between two landmasses that connects two larger bodies of water.

Bass Strait is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterway between the Great Australian Bight and the Tasman Sea, and is also the only maritime route into the economically prominent Port Phillip Bay.

Formed 8,000 years ago by rising sea levels at the end of the last glacial period, the strait was named after English explorer and physician George Bass (1771–1803) by European colonists.

Sahul (/səˈhuːl/), also called Sahul-land, Meganesia, Papualand and Greater Australia, was a paleocontinent that encompassed the modern-day landmasses of mainland Australia, Tasmania, New Guinea, and the Aru Islands.

Sahul was in the south-western Pacific Ocean, located approximately north to south between the Equator and the 44th parallel south and west to east between the 112th and the 152nd meridians east. Sahul was separated from Sunda to its west by the Wallacean Archipelago. At its largest, when ocean levels were at their lowest, it was approximately 10,600,000 square kilometres (4,100,000 sq mi) in size.

The states and territories are the national subdivisions and second level of government of Australia. The states are partially sovereign, administrative divisions that are self-governing polities, having ceded some sovereign rights to the federal government. They have their own constitutions, legislatures, executive governments, judiciaries and law enforcement agencies that administer and deliver public policies and programs. Territories can be autonomous and administer local policies and programs much like the states in practice, but are still legally subordinate to the federal government.

Australia has six federated states: New South Wales (including Lord Howe Island), Queensland, South Australia, Tasmania (including Macquarie Island), Victoria, and Western Australia. Australia also has ten federal territories, out of which three are internal territories: the Australian Capital Territory, the Jervis Bay Territory, and the Northern Territory on the Australian mainland; and seven are external territories: the Ashmore and Cartier Islands, the Australian Antarctic Territory, Christmas Island, the Cocos (Keeling) Islands, the Coral Sea Islands, Heard Island and McDonald Islands, and Norfolk Island that are offshore dependent territories. Every state and internal territory (except the Jervis Bay Territory) is self-governing with its own independent executive government, legislature, and judicial system, while the rest only have local government status overseen by federal departments.

An old-growth forest or primary forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Nations defines primary forests as naturally regenerated forests of native tree species where there are no clearly visible indications of human activity and the ecological processes are not significantly disturbed. One-third (34 percent) of the world's forests are primary forests. Old-growth features include diverse tree-related structures that provide diverse wildlife habitats that increases the biodiversity of the forested ecosystem. Virgin or first-growth forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.

As of 2020, the world has 1.11 billion ha (2.7 billion acres) of primary forest remaining. Combined, three countries (Brazil, Canada, and Russia) host more than half (61 percent) of the world's primary forest. The area of primary forest has decreased by 81 million ha (200 million acres) since 1990, but the rate of loss more than halved in 2010–2020 compared with the previous decade.

The eastern states of Australia are the states adjoining the east continental coastline of Australia. These are the mainland states of Victoria, New South Wales and Queensland, and the island state of Tasmania. The Australian Capital Territory and Jervis Bay Territory, while not states, are also included. On some occasions, the southern state of South Australia is also included in this grouping due to its economic ties with the eastern states.

Regardless of which definition is used, the eastern states include the great majority of the Australian population. They contain the federal capital Canberra and Australia's three largest cities Sydney, Melbourne and Brisbane (all capitals of the respective east coast states). Of the 19 Australian cities with populations over 100,000 in 2021, 16 were located in the eastern states under the restricted definition (17 if including South Australia), which includes the two non-capital cities with a population over 500,000: Gold Coast, Queensland and Newcastle, New South Wales. In terms of climate, the area is dominated by a humid subtropical zone, with some tropical (Queensland) and oceanic climate (Australian Capital Territory, Victoria, New South Wales) zones. In most situations, the eastern states are defined as those who use Australian Eastern Standard Time (AEST), and that is the definition that this article will adhere to, unless noted.