Boundaries between the continents


Determining the boundaries between the continents is generally a matter of geographical convention and consensus. Several slightly different conventions are in use. The number of continents is most commonly considered seven but may range as low as four when Afro-Eurasia and the Americas are both considered as single continents. An island can be considered to be associated with a given continent by either lying on the continent's adjacent continental shelf or being a part of a microcontinent on the same principal tectonic plate. An island can also be entirely oceanic while still being associated with a continent by geology or by common geopolitical convention. Another example is the grouping into Oceania of the Pacific Islands with Australia and Zealandia.
There are three overland boundaries subject to definition:
While today the isthmus between Asia and Africa is navigable via the Suez Canal, and that between North and South America via the Panama Canal, these artificial channels are not generally accepted as continent-defining boundaries in themselves. The Suez Canal happens to traverse the Isthmus of Suez between the Mediterranean Sea and the Red Sea, dividing Africa and Asia. The continental boundaries are considered to be within the very narrow land connections joining the continents.
The remaining boundaries concern the association of islands and archipelagos with specific continents, notably:
Historically in Greco-Roman geography, "Africa" meant Ancient Libya, and its eastern extent was taken to be around Marmarica, at the Catabathmus Magnus. This was not considered to be a continent. As wider knowledge of geography developed, the shape of the African landmass became apparent. In 1806, William George Browne still titled his travelogue Travels in Africa, Egypt, and Syria. Similarly, James Bruce in 1835 published Travels through part of Africa, Syria, Egypt, and Arabia. On the other hand, as early as 1670 John Ogilby under the title Africa published "an accurate Description of the Regions of Egypt, Barbary, Libya, and Billedulgerid, the Land of Negroes, Guinea, Æthiopia, and the Abyssines, with all the adjacent Islands, either in the Mediterranean, Atlantic, Southern, or Oriental Seas, belonging thereunto".
The usual line taken to divide Africa from Asia today is at the Isthmus of Suez, the narrowest gap between the Mediterranean Sea and the Gulf of Suez, the route today followed by the Suez Canal. This makes the Sinai Peninsula geographically Asian, and Egypt a transcontinental country. Less than 2% of the Egyptian population live on the Sinai Peninsula, and hence Egypt, even though technically transcontinental, is usually considered an African country entirely and not partly Asian. But when discussing the geopolitical region of the Middle East and North Africa, Egypt is usually grouped with the Western Asian countries as part of the Middle East, while Egypt's western neighbor Libya is grouped with the remaining North African countries as the Maghreb. Both are members of the African Union. However, the geological boundary is located further to the east, along the Gulf of Aqaba and the Dead Sea Transform, with the Sinai Peninsula, Israel, Palestine, much of Lebanon and the coastal governorates of Syria being located on the African Plate.
The Comoros, Madagascar, Mauritius, and Seychelles are island countries in the Indian Ocean which are nominally associated with Africa. The Socotra Archipelago may be considered African as it lies on its continental shelf; however, it is politically a part of Yemen, an Asian country.

Africa and Europe

The African and European mainlands are non-contiguous, and the delineation between these continents is thus merely a question of which islands are to be associated with which continent.
The Portuguese Atlantic island possession of the Azores is from Europe and from Africa, and is sometimes grouped with Europe. By contrast, the Canary Islands and the Madeira islands off the Atlantic coast of Morocco are much closer to, and usually grouped with, Africa; the Canary Islands are only from the African mainland at their closest point but from the European mainland, while Madeira is from the African mainland and from the European mainland. In his 1895 book Africa: Volume 2, author Augustus Henry Keane remarked, "In the North Atlantic there are four insular groups — Madeira, the Canaries, Cape Verde and Azores — which are usually assigned to Africa, although the Canaries and Cape Verde alone belong geographically to that continent, the Azores are lost, so to say, in mid-Atlantic."
The Mediterranean island country of Malta was considered a part of Africa for centuries. However, it is much closer to the coast of Sicily than it is to the African mainland. The nearby Italian island of Lampedusa is from Sicily while just from the African mainland; similarly, Pantelleria is from Sicily and just from the African mainland. All of these Mediterranean islands, including Malta and Sicily, are actually located on the African Plate, and could be considered part of the African continent geologically. However, for political and cultural reasons, maps generally display them as part of Europe instead.
A single Spanish islet, known as Alboran Island, is also debatably located on either the African Plate or the Eurasian Plate. This island is located in the Alboran Sea, 50 km north of the Moroccan coast and 90 km south of Spain.

European-governed territories in Africa

There are six definitive occurrences of territories unequivocally being a part of the African continent, but legally being administered by a European state. Three of these are administered by France, and the other three by Spain. The existence of these territories further blurs the line between the borders of Africa and Europe, in particular with regard to the Spanish territories which lie immediately adjacent to and/or connected to the African mainland. The French territories lie within the Indian Ocean, and, consequently, are more dislocated from the principal boundary between the two continents.
The uninhabited Spanish unincorporated overseas minor territories, known as the plazas de soberanía, are small islands that lie immediately adjacent to the North African coastline, with the exception of Peñón de Vélez de la Gomera, which was originally an island like the other 'localities' but has subsequently become directly connected to the Moroccan mainland. The two other Spanish territories are the exclaves of Ceuta and Melilla, which are two populated coastal cities located directly on the African mainland, both bordering only Morocco.
Two of the French territories are the inhabited overseas departments and regions of Mayotte and Réunion. Mayotte is an island territory located west of the island country of Madagascar within the Mozambique Channel. Réunion is an island territory located near the island country of Mauritius and to the east of Madagascar. The final territory is the Scattered Islands in the Indian Ocean, administratively a part of the French Southern and Antarctic Lands. This French territory consists of a range of minor uninhabited atolls in the Indian Ocean, located in the deep sea surrounding Madagascar.

Antarctica

Antarctica along with its outlying islands have no permanent population. All land claims south of 60°S latitude are held in abeyance by the Antarctic Treaty System.
Australia's Heard Island and McDonald Islands and the French Kerguelen Islands are located on the Kerguelen Plateau, on the Antarctic continental plate. Both are still within the bounds of the Indian Ocean. The United Nations categorizes Heard Island and McDonald Islands, which are politically affiliated with Australia, as being part of Oceania. The islands are 4,000 km from Perth in Australia, and have never been inhabited by indigenous peoples of Oceania or any other humans. Heard Island has only been visited 240 times throughout its entire history, and the McDonald Islands have only ever been visited twice, in 1971 and 1980. The World Factbook categorizes these islands as part of Antarctica rather than Oceania.
The French Crozet Islands, Île Amsterdam, Île Saint-Paul, and the Norwegian Bouvet Island are also located on the Antarctic continental plate, and are not often associated with other continents. The United Nations categorize Bouvet Island as part of South America, while the World Factbook categorizes it as part of Antarctica.
South Georgia and the South Sandwich Islands are closer to Antarctica than to any other continent. However, they are politically associated with the Falkland Islands, which are less geographically isolated from South America. Furthermore, Argentina, a South American country, maintains its irredentist claims on all of these islands, which are administered by the United Kingdom. The United Nations consider them to be part of South America. Definitions of South America that exclude the Galápagos Islands and Juan Fernández Islands still generally include the Falklands, which share biographical affinities to Patagonia and Tierra del Fuego, and which are located on the South American continental shelf. The Falkland Islands and South Georgia and the South Sandwich Islands were uninhabited when discovered by Europeans, with some theorizing that the Falklands were visited by Indigenous peoples of the Americas during prehistoric times. These theories are usually considered dubious, as there is no archaeological evidence indicating prehistoric human inhabitation on the Falklands. South Georgia and the South Sandwich Islands do not have any permanent residents. The Falkland Islands have historically had a British population, with a culture distinct from that of mainland South America. There was a violent war between Argentina and the United Kingdom regarding ownership of the islands in 1982, and the residents of the Falklands do not currently wish to be associated with South America, despite their geographical proximity.
The Prince Edward Islands are located between Africa and Antarctica, and are the territory of South Africa, an African country.
Macquarie Island and the Antipodes Islands, Auckland Islands, and Campbell Islands are all uninhabited, and are located between Australia and New Zealand and Antarctica. The Antipodes Islands, Auckland Islands and Campbell Islands are politically part of New Zealand, while Macquarie Island has been integrated into the Australian state of Tasmania. None are discrete political entities like Heard Island and McDonald Islands. As such, they are likely considered by the United Nations also to be part of Oceania. The Auckland Islands could be considered part of Oceania on cultural grounds rather than mere political grounds, as they are believed to be the southernmost island group to have been settled by Polynesians during prehistoric times. The islands were uninhabited when discovered by Europeans, but archaeological traces have since been found to indicate Polynesian settlement, dating to the 13th century, on Enderby Island. Macquarie Island is theorized to have possibly had contact with Polynesians, although there is no archaeological evidence to support this.