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 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 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. 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 canals running from coast to coast (e.g. the Panama Canal), 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 in the Middle America, the Kra Isthmus on

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 between North Africa and Western Asia, and the Karelian Isthmus in Europe. 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 ...

in Greece and the Isthmus of Catanzaro in Italy.

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 and Pacific Oceans; 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 and the Red Sea, cutting across the western side of the Isthmus of Suez, formed by the Sinai Peninsula; and the Crinan Canal crosses the isthmus between Loch Crinan 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 peninsula with the rest of Scotland. Another example is the Welland Canal 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 to Lake Erie. The city of Auckland 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 ...

of New Zealand is situated on an isthmus.

Notes

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Isthmus vs land bridge vs peninsula

Major isthmuses

Canals

See also

Notes