The nature and boundaries between Europe and Asia is more a sociopolitical question than a geographical one, since there is no tectonic plate boundary separating the two. Many geologists and geographers agree that Europe and Asia share many common geographical features and they are in many geological respects the single continent Eurasia. While Europe is considered a geographical entity, it is done so as a super-peninsula of the mainland of Asia, as is for example, the Indian subcontinent, which even resides on a different tectonic plate than the rest of Asia and Europe.
The eastern boundary of Europe has been variously defined since antiquity. Herodotus regarded Europe as extending all the way to the Eastern Ocean, and being as long as (and much larger than) Africa and Asia together. The modern world is in consensus that Europe ends at the Aegean Sea, the Black Sea, the Caspian Sea and the Ural Mountains, but the boundaries between these latter three features are uncertain; that leading from the Urals to the Black Sea, for example, has been drawn by different authorities as at the Don, the Kuma-Manych Depression, the Caucasus, the Russian frontier or the Rioni River.
Some atlases state that the Europe-Asia boundary follows the watershed of the Ural Mountains from near Kara, Russia on the Kara Sea to the source of the Ural River, then follows that river to the Caspian Sea. The border then follows the watershed of the Caucasus Mountains from the Caspian Sea to the Black Sea.
By this definition, the Greater Caucasus mountains are on the border of Europe and Asia. Mount Elbrus is north of the watershed divide and would be entirely in Europe by this definition, making it the highest point in Europe. The Lesser Caucasus is located entirely in Asia by this same criterion. The Turkish city Istanbul lies in both Europe and Asia, making it a transcontinental city. Georgia and Azerbaijan both have most of their territory in Asia, although each has small parts of its northern territory in Europe.
Russia and Kazakhstan have both European (western) and Asian (eastern) parts. While Russia is generally considered a European country that extends into Asia, Kazakhstan is considered a Central Asian country that extends into Europe.
Three nations of the South Caucasus Georgia, Azerbaijan, and Armenia have a strong sociopolitical claim to be European. Of the three, only Georgia and Azerbaijan are generally regarded as having portions of territory in Europe, but Armenia may be regarded as European for cultural and historical reasons. All three, however, are typically excluded from lists of European states and included in lists of Asian states.
According to the Russian definition, the boundary between Europe and Asia runs along the Mugodzhar Hills, then down the Emba River to the Caspian Sea. From the Caspian Sea it runs to the Black Sea along the Kuma-Manych Depression, marked by the rivers of the same name. This definition from Strahlenberg was in use by Russian geographers since the mid-18th century; it was officially recommended for use in textbooks by the Geographical Society of USSR in 1958. Strahlenberg's definition is also common in German-language regions. It places all of the Caucasus, including countries of Georgia and Azerbaijan and North Caucasian republics of Chechnya and Dagestan, entirely in Asia.
Russia's Vaygach Island and Novaya Zemlya extend northward from the northern end of the Ural Mountains and are a continuation of the chain into the Arctic Ocean. They separate the European Barents Sea and the Asian Kara Sea, and may be considered part of Europe or Asia. The maps on this page show them within Europe. The Russian Arctic archipelago of Franz Josef Land farther north is also associated with Europe. All of these Arctic islands are part of the European Arkhangelsk Oblast.
Other nations have some cultural ties with Europe, such as the northern African states of Morocco, Algeria, Tunisia and Egypt. At the same time, they have stronger cultural ties with the Arab world. Additionally, the clear boundary of the Mediterranean Sea excludes these nations geographically. Some in Egypt, Israel, Morocco, Tunisia and Cape Verde have shown ambition to become a state of the European Union, but currently full membership is disallowed (Morocco applied to join, but was rejected on geographical grounds). Of course, many other countries outside Europe have cultural and historical ties to Europe as a consequence of colonization and migration. Other countries such as the United States, Canada, Australia, New Zealand and the region Latin America may therefore also be considered ″culturally European states″.
Europe ends in the west at the Atlantic Ocean, although Iceland and the Azores archipelago (in the Atlantic, between Europe and North America) are usually considered European, as is the Norwegian Svalbard archipelago in the Arctic Ocean. Greenland is geographically associated with North America but politically associated with Europe (as it is still part of Denmark, although EU law no longer applies there). Turkey, despite having only 3% of its land in Europe, has been a member of the Council of Europe since 1949 and an official candidate for membership of the European Union since 2005. Islands geographically associated with one continent sometimes have stronger political and cultural ties to another. For example, Cyprus, an island geographically a part of Asia, was admitted to the Council of Europe in 1961 and joined the EU in 2004. Cape Verde, an island group off the Atlantic coast of Africa, has also shown an interest in joining the EU. Armenia, Georgia, and Azerbaijan, also geographically Asian states (although Azerbaijan and Georgia have a part of their land in Europe,) have all joined the Council of Europe.
The natural geographical boundaries of Africa are the Mediterranean Sea, the Red Sea, and the Gulf of Aden. The boundary between Africa and Asia is usually from the Gulf of Suez, or less frequently, from the Gulf of Aqaba. On purely geological grounds, the boundary could be drawn along the fault-line into the Jordan River valley (which would make Israel, Lebanon, and a small part of Syria part of Africa.)
The usual line today is at the Isthmus of Suez along the path of the Suez Canal. This makes the Sinai Peninsula geographically Asian, and Egypt a transcontinental country. A map of the recognized boundary between the two continents may be viewed here. Nevertheless Egypt is commonly referred to as an African state, because most of its population and territory are there. Geopolitically, Egypt is sometimes regarded as an Asian state, and it is usually considered part of the transcontinental geopolitical region of the Middle East.
In historical geography, several of the larger Mediterranean islands have often been more akin to Africa than to Europe or Asia. Ancient Egypt often ruled Cyprus, and sometimes Crete and Rhodes. The Roman Empire grouped Crete with Cyrenaica (in ancient Libya.) The Balearic Islands and half of Sicily were ruled from Carthage.
The Canary Islands and Madeira Islands are off the Atlantic coast of Morocco, and although they are geographically part of Africa, they are under the rule of Spain and Portugal, respectively, and geopolitically part of Europe. Prior to Southwest European colonization, they were fully integrated into Africa.
Mayotte, situated in the Mozambique Channel between Africa and Madagascar (also geographically part of Africa) is under the rule of France, as are Réunion Island east of Madagascar and some scattered islands in the Indian Ocean also associated with Africa. The Seychelles, Mauritius, and Comoros are island nations also associated with Africa.
The boundaries between Europe and Africa are almost entirely clear-cut and undisputed, since the two continents occupy opposite sides of the Mediterranean Sea, of which the midway areas are mostly devoid of islands. Spain owns the exclaves of Ceuta and Melilla on the African mainland. Sicily and Malta form a cultural extension of Europe into the heart of the Mediterranean, with only the Italian island of Pantelleria falling into question, surrounded by Malta (European) and the Pelagie Islands (African).
Both Sicily and Malta are located on a continental crustal prong  of the African tectonic plate  known as the Sicilian-Tunisian Platform, with Malta lying closer to Sicily than to Africa. The islands of Malta were indeed formed from the high points of a land bridge between Sicily and North Africa which became isolated as sea levels rose after the last Ice Age  Although Malta and Sicily were ruled by Arabs, the historical links thus forged between the African continent and the islands have now been largely lost. The Italian island of Pantelleria is situated at the join between the European and African tectonic plates, being in fact a volcanic island, and is as such geographically neither part of Europe or Africa, although politically and culturally European. The Italian Pelagie Islands are actually situated on the African continent, making them geographically African, but as with Pantelleria, is culturally assimilated to Europe.
The Portuguese Atlantic island possession of the Azores is slightly closer to Europe than Africa and is politically and culturally associated with Europe.
The boundaries between Africa and South America are clear-cut and undisputed, since the two continents occupy opposite sides of the Atlantic Ocean, of which the midway areas are almost devoid of islands between the continents. The uninhabited Brazilian island possessions of Saint Peter and Paul Rocks and Trindade and Martim Vaz are associated with South America whilst the British island possessions of Ascension Island, Saint Helena, Tristan da Cunha, and Gough Island are associated with Africa.
One common demarcation follows the Darién Mountains watershed divide along the Colombia-Panama boundary where the isthmus meets the South American continent. Another reckons the continental divide at the Panama Canal, whereby Panama has territory on either side in both continents. Geopolitically (i.e., not strictly geophysical), Panama is usually included with the other North American countries in Central America. The border between North and South America has also been drawn (infrequently) between Costa Rica and Panama, or at one of several other lines across the Isthmus of Panama.
This collection of lands and regions in the Western hemisphere are referred to as the Americas in English. From a sociopolitical and cultural perspective, the Americas are generally divided into Anglo-America (the U.S., Canada, and the Anglo-Caribbean countries) where English prevails and Latin America (Mexico, most of South America, and some of the Caribbean such as Cuba and Hispaniola; Haiti and the Dominican Republic) where Romance languages generally predominate. Latin America – particularly Hispanic America – is generally considered a transcontinental region straddling two continents, much like the Middle East. Moreover, the Guyanas are sometimes grouped with the Caribbean region along with Belize and Bermuda (a British possession actually 1000 km east of the US mainland, also sometimes grouped with Anglo-America.) It is not uncommon for what is geopolitically considered North America to be limited to the US, Canada, and sometimes Bermuda.
In some non-Anglophone cultures, the Americas are thought of as one continent or supercontinent (i.e., America) encompassing the entire landmass between Alaska and Tierra del Fuego. In this way, North America and South America are thought of as regions of the greater landmass. The Olympic Rings represent the Americas with a single ring.
The Galápagos Islands and Malpelo Island in the eastern Pacific Ocean are possessions of Ecuador and Colombia, respectively, and associated with South America. The uninhabited French possession of Clipperton Island 600 miles off the Mexican coast is associated with North America. France also continues to control French Guiana on the northern mainland of South America, as well as Saint-Pierre and Miquelon off the coast of Newfoundland and Martinique, Guadeloupe, Saint-Barthélemy, and Saint Martin in the North American Caribbean. The Netherlands and the United Kingdom are two other European nations that also continue to control islands in the Caribbean, and the Netherlands Antilles are considered split between North and South America.
The boundaries between Europe and North America are mostly clear-cut and undisputed, since the two continents occupy opposite sides of the North Atlantic Ocean. The midway areas of this ocean are devoid of islands, except in the north, where the line comes down to Greenland and Iceland. Iceland and the Azores are protrusions of the Mid-Atlantic Ridge and are associated with and peopled from Europe. Greenland is usually considered geographically North American and, moreover, most of the Greenlander ancestry is from the Inuit people indigenous to northern North America. The Norwegian Arctic islands of Jan Mayen and Svalbard archipelago are associated with Europe, because they are much closer to Europe than to the North American mainland.
The Bering Strait and Bering Sea separate the landmasses of Asia and North America, as well as forming the international boundaries between Russia and the United States, respectively. This national and continental boundary separates the Diomede Islands in the Bering Strait, with Big Diomede in Russia and Little Diomede in the US. The Aleutian Islands are an island chain extending westward from the Alaska Peninsula toward Russia's Komandorski Islands and Kamchatka Peninsula, as well as an integral part of the transcontinental American state of Alaska. Most of them are associated with North America, except for the westernmost Near Islands group, which is on Asia's continental shelf beyond the North Aleutians Basin and allows the US to be considered a transcontinental country without Hawaii and other Oceanian island possessions.
The US therefore is situated in central and northwestern North America, northeastern Asia, and Oceania. St. Lawrence Island in the northern Bering Sea belongs to Alaska and may be associated with either continent, as may the Rat Islands in the Aleutian chain. The western Aleutian Islands belong to the transcontinental Aleutians West Census Area. St. Lawrence Island belongs to the Nome Census Area, which is also transcontinental if the island is associated with Asia.
Indonesia is today more commonly referred to as one of the Southeast Asian countries, and thus simply Asian. East Timor, an independent state that was formerly a territory of Indonesia, is sometimes considered part of Oceania, but is classified by the United Nations as part of the "South-Eastern Asia" block. It is expected to join the Association of Southeast Asian Nations , having been involved as an ASEAN Regional Forum member since independence, and has participated in the Southeast Asian Games since 2003.
Antarctica and its outlying islands have no permanent population. All land south of 60°S latitude is terra nullius and the Antarctic Treaty System holds all claims to such land in abeyance. Although South Georgia and the South Sandwich Islands are closer to Antarctica, the inhabited Falkland Islands are closer to South America and the continental boundary separates them from the South Georgia group. These South Atlantic island groups were the object of contention in the Falklands War between the United Kingdom and Argentina, which maintains its irredentist claims on the islands.
The following are sub-Antarctic island territories north of 60° and associated with Antarctica: