View source for Isthmus

{{Short description|Narrow strip of land connecting two larger land areas}}
{{Other uses}}
[[File:The Spit Bruny Island.jpg|thumb|upright|The sandy isthmus or [[tombolo]] "The Neck" connects North and South [[Bruny Island]] in [[Tasmania]], [[Australia]]]]

An '''isthmus''' ({{IPAc-en|ˈ|ɪ|s|(|θ|)|m|ə|s}} {{respell|ISS|məs|,_|ISTH|məs}};<ref name="CollinsDict">{{cite Collins Dictionary|isthmus |access-date=2016-12-19}}</ref> {{plural form}}: '''isthmuses''' or '''isthmi''' {{IPAc-en|-|m|aɪ}} {{respell|-|my}};<ref name="CollinsDict"/> from [[Ancient Greek]] {{wikt-lang|grc|ἰσθμός}} {{grc-transl|ἰσθμός}} {{gloss|neck}})<ref>{{LSJ|*)isqmo/s|ἰσθμός|ref}}</ref> is a [[land bridge|narrow piece of land connecting two larger areas]] across an expanse of water by which they are otherwise separated.<ref>{{cite EBO |title=isthmus |url=https://www.britannica.com/EBchecked/topic/297042/isthmus |access-date=September 22, 2013}}</ref> A [[tombolo]] is an isthmus that consists of a [[spit (landform)|spit]] or [[shoal|bar]], and a [[strait]] 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''==
[[File:Aerial perspective of the isthmus of Bruny Island.jpg|thumb|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 land masses. The term ''land bridge'' is usually used in [[biogeology]] 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, such as [[Beringia]] and [[Doggerland]].<ref>{{Cite web|url=https://www.britannica.com/science/land-bridge|title=Land bridge &#124; isthmus|website=Encyclopedia Britannica}}</ref>

An isthmus is a land connection between two bigger landmasses, while a [[peninsula]] 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]]s running from coast to coast (e.g., the [[Panama Canal]]), and thus resemble two peninsulas; however, canals are artificial features, as distinguished from naturally occurring [[strait]]s.<ref>{{Cite web |title=strait |url=https://kids.britannica.com/students/article/strait/633562 |access-date=2025-06-19 |website=Britannica Kids |language=en-US}}</ref>

==Major isthmuses==
[[File:Karelian Isthmus.png|thumb|[[Karelian Isthmus]] in [[Russia]], which lies between the [[Gulf of Finland]] and [[Lake Ladoga]]]]

The world's major isthmuses include:

* [[Karelian Isthmus]] in [[Europe]] 
* [[Kra Isthmus]] in [[Mainland Southeast Asia]] 
* [[Bird's Neck Isthmus]] in Western New Guinea
* [[Isthmus of Tehuantepec]] in [[Middle America (Americas)|Middle America]] 
* [[Isthmus of Perekop]] in Ukraine
* [[Isthmus of Panama]] in [[Middle America (Americas)|Middle America]]
* [[Isthmus of Suez]] between [[North Africa]] and [[Western Asia]]

Of historic importance were:

* [[Isthmus of Catanzaro]] in [[Italy]]
* [[Isthmus of Corinth]] in [[Greece]]

The cities of [[Auckland]], [[Madison, Wisconsin|Madison]], [[Manila]], and [[Seattle]] 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 [[Panama Canal]] crosses the [[Isthmus of Panama]], connecting the [[Atlantic Ocean|Atlantic]] and [[Pacific Ocean]]s
* The [[Suez Canal]] connects the [[Mediterranean Sea]] (part of the [[Atlantic Ocean]]) and the [[Red Sea]] (part of the [[Indian Ocean]]), cutting across the western side of the Isthmus of Suez, formed by the [[Sinai Peninsula]]
* The [[Crinan Canal]] crosses the isthmus between [[Loch Crinan]] and [[Loch Gilp]], which connects the [[Kintyre]] peninsula with the rest of Scotland
* The [[Welland Canal]] in the [[Niagara Peninsula]] (technically an isthmus); it connects [[Lake Ontario]] to [[Lake Erie]]
* The [[Corinth Canal]] connects the [[Gulf of Corinth]] in the [[Ionian Sea]] with the [[Saronic Gulf]] in the [[Aegean Sea]]
* The [[Lake Washington Ship Canal]] connects the [[Puget Sound]] to [[Lake Washington]] in Seattle via [[Lake Union]]

== See also ==
{{Portal|Geography}}
{{Commons category|Isthmi}}
* {{Annotated link|Land bridge}}
* {{Annotated link|List of isthmuses}}
* {{Annotated link|List of straits}}

== References ==
{{reflist}}

{{Coastal geography}}

{{Authority control}}

[[Category:Isthmuses|*]]