An isthmus (; : isthmuses or isthmi) 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. It is a deposition landform by which an island becomes attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. The word ''t ...

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 * Protein bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a laye ...

, and a

strait A strait is a water body connecting two seas or water basins. The surface water is, for the most part, at the same elevation on both sides and flows through the strait in both directions, even though the topography generally constricts the ...

is the sea counterpart of an isthmus, a narrow stretch of sea between two landmasses that connects two larger bodies of water.

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 colonize new lands. A land bridge can be created by marine regression, in which sea le ...

is an isthmus connecting Earth's major land masses. 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 ...

to describe land connections that used to exist between continents at various times and were important for the 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 70th parallel north, 72° north latitude in the Chukchi Sea; and on the south ...

and

Doggerland Doggerland was a large area of land in Northern Europe, now submerged beneath the southern North Sea. This region was repeatedly exposed at various times during the Pleistocene epoch due to the lowering of sea levels during glacial periods. Howe ...

. 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 only connected to land on one side. Peninsulas exist on each continent. The largest peninsula in the world is the Arabian Peninsula. Etymology The word ''peninsula'' derives , . T ...

is rather a land protrusion that 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 ...

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

Panama Canal The Panama Canal () is an artificial waterway in Panama that connects the Caribbean Sea with the Pacific Ocean. It cuts across the narrowest point of the Isthmus of Panama, and is a Channel (geography), conduit for maritime trade between th ...

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

Major isthmuses

The world's major isthmuses include: *

Karelian Isthmus The Karelian Isthmus (; ; ) is the approximately stretch of land situated between the Gulf of Finland and Lake Ladoga in northwestern Russia, to the north of the River Neva. Its northwestern boundary is a line from the Bay of Vyborg to the we ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Kra Isthmus The Kra Isthmus (, ; ), also called the Isthmus of Kra 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 Thailan ...

Mainland Southeast Asia Mainland Southeast Asia (historically known as Indochina and the Indochinese Peninsula) 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 th ...

Bird's Neck Isthmus The Bird's Neck Isthmus is an isthmus in western New Guinea. It connects the main mass of the island to its two large western peninsulas, the Bird's Head Peninsula, also known as the Vogelkop or Doberai Peninsula, and the Bomberai Peninsula. The ...

in Western New Guinea *

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 T ...

in Middle America *

Isthmus of Perekop The Isthmus of Perekop, literally Isthmus of the Trench (; transliteration: ''Perekops'kyi pereshyiok''; ; transliteration: ''Perekopskiy peresheek,'' , ; ; transliteration: ''Taphros''), is the narrow, wide strip of land that connects the C ...

in Ukraine *

Isthmus of Panama The Isthmus of Panama, 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 America, North and South America. The country of Panama is located on the i ...

in Middle America *

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

between

North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...

and

Western Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...

Of historic importance were: *

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 ...

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

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 wide Isthmus was known in the a ...

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

The cities of

Auckland Auckland ( ; ) is a large metropolitan city in the North Island of New Zealand. It has an urban population of about It is located in the greater Auckland Region, the area governed by Auckland Council, which includes outlying rural areas and ...

Madison Madison may refer to: People * Madison (name), a given name and a surname * James Madison (1751–1836), fourth president of the United States * Madison (footballer), Brazilian footballer Places in the United States Populated places * Madi ...

Manila Manila, officially the City of Manila, is the Capital of the Philippines, capital and second-most populous city of the Philippines after Quezon City, with a population of 1,846,513 people in 2020. Located on the eastern shore of Manila Bay on ...

, and

Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...

are located on isthmuses.

Canals

Canals are often built across isthmuses, where they may be a particularly advantageous shortcut for marine transport. For example: * The

crosses the

, connecting the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

and

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

s * The

Suez Canal The Suez Canal (; , ') is an artificial sea-level waterway in Egypt, Indo-Mediterranean, connecting the Mediterranean Sea to the Red Sea through the Isthmus of Suez and dividing Africa and Asia (and by extension, the Sinai Peninsula from the rest ...

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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

(part of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

) and the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

(part of the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

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

Sinai Peninsula The Sinai Peninsula, or simply Sinai ( ; ; ; ), 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 land bridge between Asia and Afri ...

* The

Crinan Canal The Crinan Canal is a Canals of the United Kingdom, navigable canal in Argyll and Bute, west of Scotland. It opened in 1801 and connects the village of Ardrishaig on Loch Gilp with Crinan, Argyll, Crinan on the Sound of Jura, providing a navi ...

crosses the isthmus between

Loch Crinan Loch Crinan is a seawater loch on the West of Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern p ...

and

Loch Gilp Loch Gilp () is a small inlet on Loch Fyne, Argyll and Bute, west of Scotland. The loch gives its name to the nearby town of Lochgilphead. The Crinan Canal extends from the loch ''Loch'' ( ) is a word meaning "lake" or "inlet, sea inle ...

, which connects the

Kintyre Kintyre (, ) 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 Loch Tarbert, Argyll, East and West Loch Tarbert, Argyll, West Loch Tarbert in t ...

peninsula with the rest of Scotland * The

Welland Canal The Welland Canal is a ship canal in Ontario, Canada, and part of the St. Lawrence Seaway and Great Lakes Waterway. The canal traverses the Niagara Peninsula between Port Weller, Ontario, Port Weller on Lake Ontario, and Port Colborne on Lak ...

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 (state), New York. The Canada–United Sta ...

Lake Erie Lake Erie ( ) 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 also has the shortest avera ...

* The

Corinth Canal The Corinth Canal () is a canal in Greece that connects the Gulf of Corinth in the Ionian Sea with the Saronic Gulf in the Aegean Sea. Completed in 1893, it cuts through the narrow Isthmus of Corinth and "separates" the Peloponnese peninsula fro ...

connects the

Gulf of Corinth The Gulf of Corinth or the Corinthian Gulf (, ) is a deep inlet of the Ionian Sea, separating the Peloponnese from western mainland Greece. It is bounded in the east by the Isthmus of Corinth which includes the shipping-designed Corinth Canal and ...

in the

Ionian Sea The Ionian Sea (, ; or , ; , ) is an elongated bay of the Mediterranean Sea. It is connected to the Adriatic Sea to the north, and is bounded by Southern Italy, including Basilicata, Calabria, Sicily, and the Salento peninsula to the west, ...

with the

Saronic Gulf The Saronic Gulf ( Greek: Σαρωνικός κόλπος, ''Saronikós kólpos'') or Gulf of Aegina in Greece is formed between the peninsulas of Attica and Argolis and forms part of the Aegean Sea. It defines the eastern side of the isthmus of C ...

in the

Aegean Sea The Aegean Sea is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans and Anatolia, and covers an area of some . In the north, the Aegean is connected to the Marmara Sea, which in turn con ...

Notes

{{Authority control *

Isthmus vs land bridge vs peninsula

Major isthmuses

Canals

See also

Notes