An isthmus (; ; ) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A

tombolo A tombolo is a sandy or shingle isthmus. A tombolo, from the Italian ', meaning 'pillow' or 'cushion', and sometimes translated incorrectly as ''ayre'' (an ayre is a shingle beach of any kind), is a deposition landform by which an island become ...

is an isthmus that consists of a spit or

bar Bar or BAR may refer to: Food and drink * Bar (establishment), selling alcoholic beverages * Candy bar * Chocolate bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a layer of cloud * Bar (u ...

, and a

strait A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean channe ...

is the sea counterpart of an isthmus.

Isthmus vs land bridge vs peninsula

Aerial perspective of the isthmus of Bruny Island

''Isthmus'' and ''land bridge'' are related terms, with isthmus having a broader meaning. A

land bridge In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and Colonisation (biology), colonize new lands. A land bridge can be created by marine regre ...

is an isthmus connecting Earth's major landmasses. The term ''land bridge'' is usually used in

biogeology Biogeology is the study of the interactions between the Earth's biosphere and the lithosphere. Biogeology examines biotic, hydrologic, and terrestrial systems in relation to each other, to help understand the Earth's climate, oceans, and other e ...

to describe land connections that used to exist between continents at various times and were important for migration of people and various species of animals and plants, e.g.

Beringia Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72 degrees north latitude in the Chukchi Sea; and on the south by the tip ...

and

Doggerland Doggerland was an area of land, now submerged beneath the North Sea, that connected Britain to continental Europe. It was flooded by rising sea levels around 6500–6200 BCE. The flooded land is known as the Dogger Littoral. Geological sur ...

. An isthmus is a land connection between two bigger landmasses, while a

peninsula A peninsula (; ) is a landform that extends from a mainland and is surrounded by water on most, but not all of its borders. A peninsula is also sometimes defined as a piece of land bordered by water on three of its sides. Peninsulas exist on all ...

is rather a land protrusion which is connected to a bigger landmass on one side only and surrounded by water on all other sides. Technically, an isthmus can have

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface flow un ...

s running from coast to coast (e.g. the

Panama Canal The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a conduit ...

), and thus resemble two peninsulas; however, canals are artificial features distinguished from

Major isthmuses

The world's major isthmuses include the

Isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country ...

and the

Isthmus of Tehuantepec The Isthmus of Tehuantepec () is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. Before the opening of the Panama Canal, it was a major overland transport route known simply as the Te ...

in the Middle America, the

Kra Isthmus The Kra Isthmus ( th, คอคอดกระ, ) in Thailand is the narrowest part of the Malay Peninsula. The western part of the isthmus belongs to Ranong Province and the eastern part to Chumphon Province, both in Southern Thailand. The ...

Mainland Southeast Asia Mainland Southeast Asia, also known as the Indochinese Peninsula or Indochina, is the continental portion of Southeast Asia. It lies east of the Indian subcontinent and south of Mainland China and is bordered by the Indian Ocean to the west an ...

, the

Isthmus of Suez The Isthmus of Suez is the land bridge"Suez Canal ...

between

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

and

Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...

, and the

Karelian Isthmus The Karelian Isthmus (russian: Карельский перешеек, Karelsky peresheyek; fi, Karjalankannas; sv, Karelska näset) is the approximately stretch of land, situated between the Gulf of Finland and Lake Ladoga in northwestern ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. Of historic importance were the

Isthmus of Corinth The Isthmus of Corinth (Greek: Ισθμός της Κορίνθου) is the narrow land bridge which connects the Peloponnese peninsula with the rest of the mainland of Greece, near the city of Corinth. The word "isthmus" comes from the Ancien ...

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...

and the

Isthmus of Catanzaro 240px, Satellite view of the isthmus. The Isthmus of Catanzaro (or ''Isthmus of Marcellinara'', also called ''Saddle of Catanzaro'' or ''Saddle of Marcellinara'' due to its morphology) is a narrow strip of land separating the Ionian Sea from the Ty ...

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

Canals

Canals are often built across isthmuses, where they may be a particularly advantageous shortcut for marine transport. For example, the Panama Canal crosses the

, connecting the North

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

and

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

s; the

Suez Canal The Suez Canal ( arz, قَنَاةُ ٱلسُّوَيْسِ, ') is an artificial sea-level waterway in Egypt, connecting the Mediterranean Sea to the Red Sea through the Isthmus of Suez and dividing Africa and Asia. The long canal is a popular ...

connects the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

and the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...

, cutting across the western side of the Isthmus of Suez, formed by the

Sinai Peninsula The Sinai Peninsula, or simply Sinai (now usually ) (, , cop, Ⲥⲓⲛⲁ), is a peninsula in Egypt, and the only part of the country located in Asia. It is between the Mediterranean Sea to the north and the Red Sea to the south, and is a l ...

; and the Crinan Canal crosses the isthmus between

Loch Crinan Loch Crinan is a seawater loch on the West of Scotland, leading into the Sound of Jura and being the western end of the Crinan Canal. The village of Crinan is at the entrance to the canal at the eastern end of the loch. Duntrune Castle stands o ...

and

Loch Gilp Loch Gilp (Scottish Gaelic: "Loch Gilb") is a small inlet on Loch Fyne which gives its name to Lochgilphead. The Crinan Canal extends from the loch across to Crinan Crinan is a name of Gaelic origin and it has a number of contexts: * Crinan, Arg ...

, which connects the

Kintyre Kintyre ( gd, Cinn Tìre, ) is a peninsula in western Scotland, in the southwest of Argyll and Bute. The peninsula stretches about , from the Mull of Kintyre in the south to East and West Loch Tarbert in the north. The region immediately north ...

peninsula with the rest of Scotland. Another example is the

Welland Canal The Welland Canal is a ship canal in Ontario, Canada, connecting Lake Ontario and Lake Erie. It forms a key section of the St. Lawrence Seaway and Great Lakes Waterway. Traversing the Niagara Peninsula from Port Weller in St. Catharines t ...

in the

Niagara Peninsula The Niagara Peninsula is an area of land lying between the southwestern shore of Lake Ontario and the northeastern shore of Lake Erie, in Ontario, Canada. Technically an isthmus rather than a peninsula, it stretches from the Niagara River in the ...

(technically an isthmus). It connects

Lake Ontario Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York. The Canada–United States border sp ...

Lake Erie Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has t ...

. The city of

Auckland Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...

on the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

is situated on an