Papua New Guinea in the context of "Torres Strait"

Oceania (UK: /ˌoʊsiˈɑːniə, ˌoʊʃi-, -ˈeɪn-/ OH-s(h)ee-AH-nee-ə, -⁠AY-, US: /ˌoʊʃiˈæniə, -ˈɑːn-/ OH-shee-A(H)N-ee-ə) is a geographical region including Australasia, Melanesia, Micronesia, and Polynesia. Outside of the English-speaking world, Oceania is generally considered a continent, while Mainland Australia is regarded as its continental landmass. Spanning the Eastern and Western hemispheres, at the centre of the water hemisphere, Oceania is estimated to have a land area of about 9,000,000 square kilometres (3,500,000 sq mi) and a population of around 46.3 million as of 2024. Oceania is the smallest continent in land area and the second-least populated after Antarctica.

Oceania has a diverse mix of economies from the highly developed and globally competitive financial markets of Australia, French Polynesia, Hawaii, New Caledonia, and New Zealand, which rank high in quality of life and Human Development Index, to the much less developed economies of Kiribati, Papua New Guinea, Tuvalu, Vanuatu, and Western New Guinea. The largest and most populous country in Oceania is Australia, and the largest city is Sydney. Puncak Jaya in Indonesia is the highest peak in Oceania at 4,884 m (16,024 ft).

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.

Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian and Pacific oceans. Comprising over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guinea, Indonesia is the world's largest archipelagic state and the 14th-largest country by area, at 1,904,569 square kilometres (735,358 square miles). With over 280 million people, Indonesia is the world's fourth-most-populous country and the most populous Muslim-majority country. Java, the world's most populous island, is home to more than half of the country's population.

Indonesia operates as a presidential republic with an elected legislature and consists of 38 provinces, nine of which have special autonomous status. Jakarta, the largest city, is the world's second-most-populous urban area. Indonesia shares land borders with Papua New Guinea, Timor-Leste, and East Malaysia, as well as maritime borders with Singapore, Peninsular Malaysia, Vietnam, Thailand, the Philippines, Australia, Palau, and India. Despite its large population and densely populated regions, Indonesia has vast areas of wilderness that support one of the world's highest levels of biodiversity.

The Malay Archipelago is the archipelago between Mainland Southeast Asia and Australia, and is also called Insulindia or the Indo-Australian Archipelago. The name was taken from the 19th-century European concept of a Malay race, later based on the distribution of Austronesian languages. It has also been called the "Malay world", "Nusantara", and the "East Indies" over time. The name is controversial in Indonesia due to its ethnic connotations and colonial undertones, which can overshadow the country's diverse cultures.

Situated between the Indian and Pacific oceans, the archipelago of over 25,000 islands and islets is the largest archipelago by area and fifth by number of islands in the world. It includes Brunei, East Timor, Indonesia, Malaysia (specifically East Malaysia), Papua New Guinea, the Philippines, and Singapore. The term is largely synonymous with Maritime Southeast Asia.

The House of Windsor is the current royal house of the United Kingdom and other Commonwealth realms. The house's name was inspired by the historic Windsor Castle estate. The house was founded on 17 July 1917, when King George V changed the name of the royal house from the German Saxe-Coburg and Gotha to the English Windsor due to anti-German sentiment during the First World War. There have been five British monarchs of the House of Windsor: George V, Edward VIII, George VI, Elizabeth II, and Charles III. The children and male-line descendants of Queen Elizabeth II and Prince Philip, Duke of Edinburgh, also genealogically belong to the House of Oldenburg since Philip was by birth a member of the Glücksburg branch of that house.

The monarch is head of state of fifteen sovereign states. These are the United Kingdom, Antigua and Barbuda, Australia, The Bahamas, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Solomon Islands, and Tuvalu. As well as these separate monarchies, there are also three Crown Dependencies, fourteen British Overseas Territories, two associated states of New Zealand, and one territory.

Western New Guinea, also known as Papua, Indonesian New Guinea, and Indonesian Papua, is the western half of the island of New Guinea, formerly Dutch and granted to Indonesia in 1962. Given the island is alternatively named Papua, the region is also called West Papua (Indonesian: Papua Barat). It is one of the seven geographical units of Indonesia in ISO 3166-2:ID.

Lying to the west of Papua New Guinea and geographically a part of the Australian continent, the territory is almost entirely in the Southern Hemisphere and includes the Biak and Raja Ampat archipelagoes. The region is predominantly covered with rainforest where traditional peoples live, including the Dani of the Baliem Valley. A large proportion of the population live in or near coastal areas. The largest city is Jayapura.

New Guinea (Tok Pisin: Niugini; Hiri Motu: Niu Gini; Indonesian: Papua, fossilized Nugini, also known as Papua or historically Irian) is the world's second-largest island, with an area of 785,753 km (303,381 sq mi). It has the third-largest remaining rainforest globally, and the highest plant biodiversity of any island. Located in Melanesia in the southwestern Pacific Ocean, the island is separated from Australia by the 150-kilometre (81-nautical-mile; 93-mile) wide Torres Strait, though both landmasses lie on the same continental shelf, and were united during episodes of low sea level in the Pleistocene glaciations as the combined landmass of Sahul. Numerous smaller islands are located to the west and east. The island's name was given by Spanish explorer Yñigo Ortiz de Retez during his maritime expedition of 1545 because of the perceived resemblance of the indigenous peoples of the island to those in the African region of Guinea.

The eastern half of the island is the major land mass of the nation of Papua New Guinea. The western half, known as Western New Guinea, forms a part of Indonesia and is organized as the provinces of Papua, Central Papua, Highland Papua, South Papua, Southwest Papua, and West Papua. The two major cities on the island are Port Moresby and Jayapura.

The Federated States of Micronesia (/ˌmaɪkroʊˈniːʒə/ , abbreviated FSM), or simply Micronesia, is an island country in Micronesia, a region of Oceania. The federation encompasses the majority of the Caroline Islands (excluding Palau) and consists of four states—from west to east: Yap, Chuuk, Pohnpei, and Kosrae—that span the western Pacific just north of the equator for a longitudinal distance of almost 2,700 km (1,700 mi). Together, the states comprise around 607 islands and a combined land area of approximately 702 km or 271 sq mi.

The entire island nation lies across the northern Pacific accordingly: northeast of Indonesia and Papua New Guinea, south of Guam and the Marianas, west of Nauru and the Marshall Islands, east of Palau and the Philippines, about 2,900 km (1,800 mi) north of eastern Australia, 3,400 km (2,100 mi) southeast of Japan, and some 4,000 km (2,485 mi) southwest of Honolulu of the Hawaiian Islands.