quality:corruption, structural:summarization
Early interpretations

French writer Gustave d'Eichthal remarked in 1844 that, "the boundaries of Oceania are in reality those of the great ocean itself." Conrad Malte-Brun in 1824 defined Oceania as covering Australia, New Zealand, the islands of Polynesia (which then included all the Pacific islands) and the Malay Archipelago. American lexicographer Joseph Emerson Worcester wrote in 1840 that Oceania is "a term applied to a vast number of islands which are widely dispersed in the Pacific Ocean they are considered as forming a fifth grand division of the world." He also viewed Oceania as covering Australia, New Zealand, the Malay Archipelago and the islands of Melanesia, Micronesia, and Polynesia. In 1887, the Royal Asiatic Society of Great Britain and Ireland referred to Australia as the area's westernmost land, while in 1870, British Reverend Alexander Mackay identified the Bonin Islands as its northernmost point, and Macquarie Island as its southernmost point. The Bonin Islands at that time were a possession of Britain; Macquarie Island, to the south of Tasmania, is a subantarctic island in the Pacific. It was politically associated with Australia and Tasmania by 1870.

Alfred Russel Wallace believed in 1879 that Oceania extended to the Aleutian Islands, which are among the northernmost islands of the Pacific. The islands, now politically associated with Alaska, have historically had inhabitants that were related to Indigenous Americans, in addition to having non-tropical biogeography similar to that of Alaska and Siberia. Wallace insisted while the surface area of this wide definition was greater than that of Asia and Europe combined, the land area was only a little greater than that of Europe. American geographer Sophia S. Cornell claimed that the Aleutian Islands were not part of Oceania in 1857. She stated that Oceania was divided up into three groups; Australasia (which included Australia, New Zealand, and the Melanesian islands), Malesia (which included all present-day countries within the Malay Archipelago, not the modern country of Malaysia) and Polynesia (which included both the Polynesian and Micronesian islands in her definition). Aside from mainland Australia, areas that she identified as of high importance were Borneo, Hawaii, Indonesia's Java and Sumatra, New Guinea, New Zealand, the Philippines, French Polynesia's Society Islands, Tasmania, and Tonga.

American geographer Jesse Olney 's 1845 book A Practical System of Modern Geography stated that it "comprises the numerous isles of the Pacific, lying south east of Asia." Olney divided up Oceania into three groups; Australasia (which included Australia, New Guinea, and New Zealand), Malesia and Polynesia (which included the combined islands of Melanesia, Micronesia, and Polynesia in his definition). Publication Missionary Review of the World claimed in 1895 that Oceania was divided up into five groups; Australasia, Malesia, Melanesia, Micronesia, and Polynesia. It did not consider Hawaii to be part of Polynesia, due to its geographic isolation, commenting that Oceania also included, "isolated groups and islands, such as the Hawaiian and Galápagos." In 1876, French geographer Élisée Reclus labelled Australia's flora as "one of the most characteristic on the globe", adding that "the Hawaiian archipelago also constitutes a separate vegetation zone; of all tropical insular groups it possesses the relatively largest number of endemic plants. In the Galápagos group also more than half of the species are of local origin." Rand McNally & Company, an American publisher of maps and atlases, claimed in 1892 that, "Oceania comprises the large island of Australia and the innumerable islands of the Pacific Ocean" and also that the islands of the Malay Archipelago "should be grouped in with Asia." British linguist Robert Needham Cust argued in 1887 that the Malay Archipelago should be excluded since it had participated in Asian civilization. Cust considered Oceania's four subregions to be Australasia, Melanesia, Micronesia and Polynesia. New Zealand was categorized by him as being in Polynesia; and the only country in his definition of Australasia was Australia. His definition of Polynesia included both Easter Island and Hawaii, which had not yet been annexed by either Chile or the United States.

The Journal of the Royal Statistical Society stated in 1892 that Australia was a large island within Oceania rather than a small continent. It additionally commented:

it is certainly not necessary to consider the Hawaiian Islands and Australia as being in the same part of the world, it is however permissible to unite in one group all the islands which are scattered over the great ocean. It should be remarked that if we take the Malay Archipelago away from Oceania, as do generally the German geographers, the insular world contained in the great ocean is cut in two, and the least populated of the five parts of the world is diminished in order to increase the number of inhabitants of the most densely populated continent.

Regarding Australia and the Pacific, Chambers's New Handy Volume American Encyclopædia observed in 1885 that, "the whole region has sometimes been called Oceania, and sometimes Australasia—generally, however, in modern times, to the exclusion of the islands in the archipelago, to which certain writers have given the name of Malesia." It added there was controversy over the exact limits of Oceania, saying that, "scarcely any two geographers appear to be quite agreed upon the subject". British physician and ethnologist James Cowles Prichard claimed in 1847 that the Aleutian Islands and the Kuril Islands form "the northern boundary of this fifth region of the world, and with the coasts of Asia and America completing its literal termination." However, he wrote that these islands "are not usually reckoned as belonging to it, because they are known to be inhabited by races of people who came immediately from the adjacent continents and are unconnected with those tribes of the human race who peopled the remote islands of this great ocean." He added that Hawaii was the most northerly area to be inhabited by races associated with Oceania.

The 1926 book Modern World History, 1776 – 1926, by Alexander Clarence Flick, considered Oceania to include all islands in the Pacific, and associated the term with the Malay Archipelago, the islands of Melanesia, Micronesia, and Polynesia, the Aleutian Islands, Japan's Ryukyu Islands, Taiwan and the Kuril Islands. He further included in his definition Sakhalin, an island which is geologically part of the Japanese Archipelago, but that has been administered by Russia since World War II. Hong Kong, partly located in another marginal sea of the Pacific (the South China Sea) was also included in his definition. Australia and New Zealand were grouped together by Flick as Australasia, and categorized as being in the same area of the world as the islands of Oceania. Flick estimated this definition of Oceania had a population of 70,000,000, and commented that, "brown and yellow races constitute the vast majority" and that the minority of whites were mainly "owners and rulers". Hutton Webster's 1919 book Medieval and Modern History also considered Oceania to encompass all islands in the Pacific, stating that, "the term Oceania, or Oceanica, in its widest sense applies to all the Pacific Islands." Webster broke Oceania up into two subdivisions; the continental group, which included Australia, the Japanese archipelago, the Malay Archipelago and Taiwan, and the oceanic group, which included New Zealand and the islands of Melanesia, Micronesia and Polynesia.

Charles Marion Tyler's 1885 book The Island World of the Pacific Ocean considered Oceania to ethnographically encompass Australia, New Zealand, the Malay Archipelago, and the islands of Melanesia, Micronesia, and Polynesia. However, Tyler included other Pacific islands in his book as well, such as the Aleutian Islands, the Bonin Islands, the Japanese archipelago, the Juan Fernández Islands, the Kuril Islands, the Ryukyu Islands, Taiwan, California 's Channel Islands and Farallon Islands, Canada 's Vancouver Island and Queen Charlotte Islands (now known as Haida Gwaii), Chile's Chiloé Island, Ecuador's Galápagos Islands, Mexico's Guadalupe Island, Revillagigedo Islands, San Benito Islands and Tres Marías Islands, and Peru's Chincha Islands. Islands in marginal seas of the Pacific were also covered in the book, including Alaska's Pribilof Islands and China's Hainan. Tyler additionally profiled the Anson Archipelago, which during the 19th century was a designation for a widely scattered group of purported islands in the Northwestern Pacific Ocean between Japan and Hawaii. The Anson archipelago included phantom islands such as Ganges Island and Los Jardines which were proven to not exist, as well as real islands such as Marcus Island and Wake Island. Tyler described Australia as "the leviathan of the island groups of the world". In his 1857 book A Treatise on Physical Geography, Francis B. Fogg commented that "the Pacific and its dependencies may be said to contain that portion of the globe termed Oceanica or 'the Maritime World', which is divided into Australasia, Malesia and Polynesia." Fogg defined Polynesia as covering the combined islands of Melanesia, Micronesia and Polynesia, as well as the Ryukyu Islands. He added that, "besides the proceeding, the Pacific contains many other islands, of which the most important are Hainan and Formosa, on the coast of China, the Japan isles, the Kuriles, the Aleutian Islands (stretching from the New World to the Old), Vancouver Island, the Galápagos, Juan Fernández and Chiloé." Scottish academic John Merry Ross in 1879 considered Polynesia to cover the entire South and Central Pacific area, not just islands ethnographically within Polynesia. He wrote in The Globe Encyclopedia of Universal Information that, "literally interpreted, the name would include all the groups from Sumatra to the Galápagos, together with Australia." Ross further wrote, "and to this vast region the term Oceania has been applied. It is more usual at the present time, however, to exclude the archipelago."