Boundaries between the continents

Determining the boundaries between the continents is mostly about agreement among people who study the Earth. Different groups sometimes count the continents in slightly different ways. Most people in English-speaking countries say there are seven continents, but some count as few as four if they group together Afro-Eurasia and the Americas.

Islands can belong to a continent in several ways. They might sit on the same underwater part of a continent, called a continental shelf, like Singapore and the British Isles. Or they could be pieces of a larger landmass, called a microcontinent, like Madagascar and Seychelles. Some islands are far out in the ocean but are still linked to a continent because of their rocks and history, like Bermuda.

There are three main land areas where continents meet, and where people can draw the lines between them. One is between Africa and Asia at the Isthmus of Suez. Another is between Asia and Europe, which can be marked along the Turkish Straits, the Caucasus, the Urals, and the Ural River. The third is between North America and South America somewhere along the Isthmus of Panama, often following the Darién Mountains.

Even though we can now travel between Asia and Africa through the Suez Canal, and between North America and South America through the Panama Canal, these water paths are not considered the true borders between the continents. The real borders are the very narrow pieces of land that connect the big landmasses. There are also many islands and groups of islands whose connection to a continent can be tricky to decide.

Africa and Asia

People used to think Africa was only a small area near Libya. Now we know Africa is much bigger, including places like Egypt.

Today, the line between Africa and Asia is at the Isthmus of Suez, where the Suez Canal is. This makes the Sinai Peninsula part of Asia, and Egypt touches both continents. Even though a small part of Egypt is in Asia, we usually think of Egypt as part of Africa. Some groups, like the African Union, count Egypt as African, but others put it with countries in Western Asia.

Africa and Europe

The mainlands of Africa and Europe are separated. We decide their boundary by which islands belong to each continent. Some islands, like the Azores, are closer to Europe. Others, like the Canary Islands and Madeira, are closer to Africa.

There are also European-governed areas in Africa, such as Ceuta and Melilla in Spain, and Mayotte and Réunion in France. These areas make the line between Africa and Europe less clear.

Antarctica

Antarctica and its nearby islands have no permanent residents. All land claims south of 60°S latitude are paused under the Antarctic Treaty System.

Some islands, like Heard Island and McDonald Islands and the Kerguelen Islands, sit on the Antarctic continental plate but are still part of the Indian Ocean. The United Nations considers these islands, which belong to Australia, part of Oceania. These islands are far from Australia and have never been home to any people.

Other islands, such as the Crozet Islands, Île Amsterdam, and Bouvet Island, also sit on the Antarctic plate and are not usually linked to other continents. Some of these islands are considered part of South America or Antarctica, depending on the source.

Islands like South Georgia and the South Sandwich Islands are closer to Antarctica than any other continent but are politically linked to the Falkland Islands, which are near South America.

The Prince Edward Islands belong to South Africa.

Other islands, such as Macquarie Island and the Antipodes Islands, Auckland Islands, and Campbell Islands, are found between Australia, New Zealand, and Antarctica. They have no permanent residents. Some of these islands are part of New Zealand, while Macquarie Island is part of the Australian state of Tasmania.

Asia and Australia

The line between Asia and Australia is in the Wallacean region of the Malay Archipelago. This boundary is often shown along the Melanesian Line or Weber's Line. Geologically, the Aru Islands in Maluku Province and western New Guinea, which include six provinces of Indonesia, are part of the Australian continent. The eastern half of New Guinea belongs to Papua New Guinea, which is part of Oceania.

Indonesia is usually a Southeast Asian country. But its eastern region of Western New Guinea and nearby islands lie between two continents. Western New Guinea is often seen as part of Oceania because of its people and its geological connection to Australia. East Timor, now an independent state formerly part of Indonesia, is classified by the United Nations as part of the South-eastern Asia subregion. It joined the Association of Southeast Asian Nations after independence and has taken part in the Southeast Asian Games since 2003.

Asia and Europe

The boundary between Asia and Europe is unusual because it is mostly based on mountains and rivers north and east of the Black Sea. People have long thought of Asia and Europe as separate continents, an idea from early Greek geographers.

In modern terms, the area called Eurasia is often seen as one big landmass, and sometimes Europe is described as a smaller part of Eurasia.

The modern border between Asia and Europe is based on history and culture, so it has changed over time. One common border follows the Aegean Sea, the Turkish Straits, the Black Sea, the watershed of the Greater Caucasus, the northwestern part of the Caspian Sea, and then the Ural River and Ural Mountains to the Kara Sea. According to this definition, Georgia is a country that lies in both Europe and Asia. Similarly, Azerbaijan also has parts in both continents. Russia and Turkey both have land in Asia and Europe. Kazakhstan also has a small part in Europe, west of the Ural River. The city of Istanbul in Turkey lies on both sides of the Bosporus, making it a transcontinental city. Cities like Magnitogorsk, Orenburg, and Atyrau also lie on the Ural River, making them transcontinental cities as well.

Asia and North America

The Bering Strait and Bering Sea separate Asia and North America. This area is the boundary between Russia and the United States. It divides the Diomede Islands. Big Diomede is in Russia and Little Diomede is in the U.S.. The Aleutian Islands stretch west from the Alaskan Peninsula toward Russia's Komandorski Islands and Kamchatka Peninsula. Most of these islands are part of North America, but the westernmost Near Islands group might sometimes be considered part of Asia. St. Lawrence Island in the northern Bering Sea belongs to Alaska and is usually part of North America. At their closest points, Alaska and Russia are only 4 kilometres (2.5 miles) apart.

Europe and North America

A continent is a large piece of land that is not an island. Some islands are part of Europe for political reasons. This includes the British Isles, islands in the North Sea, Baltic Sea, and Mediterranean, and places like the Azores, Iceland, and Malta.

Europe and North America are separated by the North Atlantic ocean. Greenland is part of North America, but it is linked to Europe because it is part of the Kingdom of Denmark. Some islands in the Caribbean belong to countries like the Netherlands and France.

North America and South America

Further information: Americas

See also: Caribbean, Central America, and Middle America

Mainland

The line between North America and South America goes through the Darién Mountains where Colombia meets Panama. Most maps show Panama as part of North America or Central America.

Islands

Many Caribbean islands are grouped with North America. However, places like Aruba, Bonaire, Curaçao (ABC islands), and Trinidad and Tobago sit on the seafloor that belongs to South America. Meanwhile, Isla Aves of Venezuela and San Andrés and Providencia of Colombia sit on the seafloor of North America. Some nearby Venezuelan islands like Nueva Esparta and the Venezuelan Federal Dependencies might also be considered part of the Caribbean rather than South America.

Oceania and the Americas

The Galápagos Islands and Malpelo Island belong to Ecuador and Colombia. Even though they are close to South America, some people think they are part of Oceania because of where they are in the Pacific Ocean.

Easter Island, also called Rapa Nui, is far off the coast of Chile. Even though it is now part of Chile, its culture comes from Oceania. Other islands near Easter Island, like Salas y Gómez, the Desventuradas Islands, and the Juan Fernández Islands, are also sometimes thought of as part of Oceania because of where they are and the plants and animals that live there.