Bass Strait in the context of Lady Julia Percy Island

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.

Tasmania (/tæzˈmeɪniə/; palawa kani: Lutruwita) is an island state of Australia. It is located 240 kilometres (150 miles) to the south of the Australian mainland, and is separated from it by the Bass Strait. The state encompasses the main island of Tasmania, the 26th-largest island in the world, and the surrounding 1000 islands. It is Australia's smallest and least populous state, with 573,479 residents as of June 2023. The state capital and largest city is Hobart, with around 40% of the population living in the Greater Hobart area. Tasmania is the most decentralised state in Australia, with the lowest proportion of its residents living within its capital city.

Tasmania's main island was first inhabited by Aboriginal peoples, who today generally identify as Palawa or Pakana. It is believed that Aboriginal Tasmanians became isolated from mainland Aboriginal groups around 11,700 years ago, when rising sea levels formed Bass Strait.

Victoria, commonly abbreviated as Vic, is a state in southeastern Australia. It is the second-smallest state (after Tasmania), with a land area of 227,444 km (87,817 sq mi); the second-most-populous state (after New South Wales), with a population of over 7 million; and the most densely populated state in Australia (30.6 per km). Victoria's economy is the second-largest among Australian states and is highly diversified, with service sectors predominating.

Victoria is bordered by New South Wales to the north and South Australia to the west and is bounded by the Bass Strait to the south (with the exception of a small land border with Tasmania located along Boundary Islet), the Southern Ocean to the southwest, and the Tasman Sea (a marginal sea of the South Pacific Ocean) to the southeast. The state encompasses a range of climates and geographical features from its temperate coastal and central regions to the Victorian Alps in the northeast and the semi-arid northwest.

Boundary Islet, historically known as North East Islet, is a 2-hectare (4.9-acre) islet in the Hogan Island Group of Bass Strait, at a latitude of 39°12′ S, about 56 kilometres (35 mi) east of the southernmost point of mainland Victoria. The islet straddles the maritime border of the Australian states of Victoria and Tasmania, hence the name.

The Tasmanian portion of the islet forms that state's North East Islet Nature Reserve, gazetted on 5 April 1978. The reserve's name was conferred prior to the islet's change of name, to Boundary Islet, under Tasmanian legislation. This change was gazetted on 28 March 1990.

Port Phillip (Kulin: Narm-Narm) or Port Phillip Bay is a horsehead-shaped enclosed bay on the central coast of southern Victoria, Australia. The bay opens into the Bass Strait via a short, narrow channel known as The Rip, and is completely surrounded by localities of Victoria's two largest cities — metropolitan Greater Melbourne in the bay's main eastern portion north of the Mornington Peninsula, and the city of Greater Geelong in the much smaller western portion (known as the Corio Bay) north of the Bellarine Peninsula. Geographically, the bay covers 1,930 km (750 sq mi) and the shore stretches roughly 264 km (164 mi), with the volume of water around 25 km (6.0 cu mi). Most of the bay is navigable, although it is extremely shallow for its size — the deepest portion is only 24 m (79 ft) and half the bay is shallower than 8 m (26 ft). Its waters and coast are home to seals, whales, dolphins, corals and many kinds of seabirds and migratory waders.

Before European settlement, the area around Port Phillip was divided between the territories of the Wathaurong (west), Wurundjeri (north) and Boonwurrung (south and east) people, all part of the indigeous Kulin nation. The first Europeans to enter the bay were the crews of HMS Lady Nelson, commanded by John Murray and, ten weeks later, HMS Investigator commanded by Matthew Flinders, in 1802. Subsequent expeditions into the bay took place in 1803 to establish the first settlement in Victoria, near Sorrento, but was abandoned in 1804. Thirty years later, settlers from Tasmania returned to establish Melbourne (now Victoria's capital city) at the mouth of the Yarra River in 1835, and Geelong at Corio Bay in 1838. Today, Port Phillip is the most densely populated catchment in Australia with an estimated 5.5 million people living around the bay; Melbourne's suburbs extend around much of the northern and eastern shorelines, and the city of Geelong sprawls around Corio Bay in the bay's western arm.

The Rip is the narrow waterway entrance connecting the Bass Strait to the Port Phillip Bay in southern Victoria, Australia, and is the only route of maritime transport and thus seaport access into Melbourne and Geelong, Victoria's two largest cities and homes to Australia's largest and sixth-largest ports. Geographically, it is a roughly triangular area of water between Point Nepean on the Mornington Peninsula, Shortlands Bluff and Point Lonsdale on the Bellarine Peninsula, with these three headlands forming the Heads. Because of the strong oceanic tides being funnelled into the bay through this relatively narrow channel, and a high rocky seabed, the Rip is a dangerous stretch of water and has claimed numerous ships and many lives in history.

The Mornington Peninsula is a peninsula located in the south of Greater Melbourne, Victoria, Australia. It is surrounded by Port Phillip to the west, Western Port to the east and Bass Strait to the south, and is connected to the mainland in the north. Geographically, the peninsula begins its protrusion from the mainland in the area between Pearcedale and an area north of Frankston. The area was originally home to the Mayone-bulluk and Boonwurrung-Balluk clans, and formed part of the Boonwurrung nation's territory prior to European settlement.

Much of the peninsula has been cleared for agriculture and settlements. However, small areas of the native ecology remain in the peninsula's south and west, some of which is protected by the Mornington Peninsula National Park. In 2002, around 180,000 people lived on the peninsula and in nearby areas, most in the built-up towns on its western shorelines which are sometimes regarded as outlying suburbs of greater Melbourne; there is a seasonal population of around 270,000. On 30 June 2017, the Mornington Peninsula population was recorded at 163,847 people. However, in the peak of summer the population increases to 225,000–250,000 people each year, so that it becomes the most populous coastal holiday area in Victoria, with a larger population than Hobart.

The Bellarine Peninsula (Wadawurrung: Balla-wein or Biteyong) is a peninsula located south-west of Melbourne in Victoria, Australia, surrounded by Port Phillip, Corio Bay and Bass Strait. The peninsula, together with the Mornington Peninsula, separates Port Phillip Bay from Bass Strait. The peninsula itself was originally occupied by Indigenous Australian clans of the Wadawurrung nation, prior to European settlement in the early 19th century. Early European settlements were initially centred on wheat and grain agriculture, before the area became a popular tourist destination with most visitors arriving by paddle steamer on Port Phillip in the late 19th century.

Today, approximately 70,000 people live on the Bellarine, and this population doubles at peak periods during summer. The peninsula is a growing tourist region with a variety of beaches and seaside resorts and wineries; most of the peninsula is a part of the City of Greater Geelong.

His Majesty's Armed Survey Vessel Lady Nelson was commissioned in 1799 to survey the coast of Australia. At the time large parts of the Australian coast were unmapped and Britain had claimed only part of the continent. The British Government were concerned that, in the event of settlers of another European power becoming established in Australia, any future conflict in Europe would lead to a widening of the conflict into the southern hemisphere to the detriment of the trade that Britain sought to develop. It was against this background that Lady Nelson was chosen to survey and establish sovereignty over strategic parts of the continent.

Lady Nelson left Portsmouth on 18 March 1800 and arrived at Sydney on 16 December 1800 after having been the first vessel to reach the east coast of Australia via Bass Strait. Prior to that date all vessels had sailed around the southern tip of Tasmania to reach their destination.

The King Island emu (Dromaius novaehollandiae minor) is an extinct subspecies of emu that was endemic to King Island, in the Bass Strait between mainland Australia and Tasmania. Its closest relative may be the also extinct Tasmanian emu (D. n. diemenensis), as they belonged to a single population until less than 14,000 years ago, when Tasmania and King Island were still connected. The small size of the King Island emu may be an example of insular dwarfism. The King Island emu was the smallest of all known emus and had darker plumage than the mainland emu. It was black and brown and had naked blue skin on the neck, and its chicks were striped like those on the mainland. The subspecies was distinct from the likewise small and extinct Kangaroo Island emu (D. n. baudinianus) in a number of osteological details, including size. The behaviour of the King Island emu probably did not differ much from that of the mainland emu. The birds gathered in flocks to forage and during breeding time. They fed on berries, grass and seaweed. They ran swiftly and could defend themselves by kicking. The nest was shallow and consisted of dead leaves and moss. Seven to nine eggs were laid, which were incubated by both parents.

Europeans discovered the King Island emu in 1802 during early expeditions to the island, and most of what is known about the bird in life comes from an interview French naturalist François Péron conducted with a sealer there, as well as depictions by artist Charles Alexandre Lesueur. They had arrived on King Island in 1802 with Nicolas Baudin's expedition, and in 1804 several live and stuffed King and Kangaroo Island emus were sent to France. The two live King Island specimens were kept in the Jardin des Plantes, and the remains of these and the other birds are scattered throughout various museums in Europe today. The logbooks of the expedition did not specify from which island each captured bird originated, or even whether they were taxonomically distinct, so their status remained unclear until more than a century later. Hunting pressure and fires started by early settlers on King Island likely drove the wild population to extinction by 1805. The captive specimens in Paris both died in 1822 and are believed to have been the last of their kind.

Torquay (/tɔːrˈkiː/ tor-KEY) is a town in Surf Coast Shire, Victoria, Australia, which faces Bass Strait, 21 km south of Geelong and is the gateway to the Great Ocean Road. It is bordered on the west by Spring Creek and its coastal features include Point Danger and Zeally Bay. At the 2021 census, Torquay had a population of 18,534.

The Borough of Queenscliffe is a local government area in the Barwon South West region of Victoria, Australia, located in the southern part of the state. It is the smallest local government area in Victoria, covering an area of 10.83 square kilometres (4.18 mi) and, in June 2018, had a population of 2,982. It includes only two settlements, which are Queenscliff and Point Lonsdale. It is situated on the south coast, south-east of Geelong on the Bellarine Peninsula south of Swan Bay and next to the Port Phillip Heads, the entrance to Port Phillip Bay from Bass Strait.

The Borough is governed and administered by the Queenscliffe Borough Council; its seat of local government and administrative centre is located at the council headquarters in Queenscliff. The Borough is named after the main settlement located in the centre of the LGA, that is Queenscliff, which is also the LGA's most populous urban centre with a population of 1,315.