View source for Lagoon

{{Short description|Shallow body of water separated from a larger one by a narrow landform}}
{{about|the geographical feature}}
[[File:BalosLagoonCreta.jpg|thumb| Balos coastal lagoon of northwestern [[Crete]]. The shallow lagoon is separated from the Mediterranean Sea by narrow shoals connecting to a small, rocky mountain.]]
[[File:Kara-Bogaz Gol from space, September 1995.jpg|thumb|[[Garabogazköl]] lagoon in [[Turkmenistan]]]]
[[File:Venice Lagoon December 9 2001.jpg|thumb|[[Venetian Lagoon]]]]

A '''lagoon''' is a shallow [[body of water]] separated from a larger body of water by a narrow [[landform]], such as a [[reef]], a [[barrier island]] or islands, a barrier peninsula, or an [[isthmus]]. Lagoons are commonly divided into ''[[coastal]] lagoons'' (or ''barrier lagoons'') and ''[[atoll]] lagoons''. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as [[Estuary|estuaries]]. Lagoons are common coastal features around many parts of the world.

==Definition and terminology==
Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposed [[shoal]], [[reef|coral reef]], or similar feature. Some authorities include [[fresh water]] bodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree of [[salinity]]. The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restricts "lagoon" to bodies of water with little or no fresh water inflow, and little or no [[Tide|tidal]] flow, and calls any [[bay]] that receives a regular flow of fresh water an "estuary". Davis does state that the terms "lagoon" and "estuary" are "often loosely applied, even in scientific literature".<ref name=Davis>{{cite book |last= Davis | first= Richard A. Jr. |title= The Evolving Coast |year= 1994 |publisher=Scientific American Library |location= New York |isbn= 978-0-7167-5042-0 |pages= [https://archive.org/details/evolvingcoast00davi/page/101 101, 107] |url= https://archive.org/details/evolvingcoast00davi/page/101 }}</ref> Timothy M. Kusky characterizes lagoons as normally being elongated parallel to the coast, while estuaries are usually drowned river valleys, elongated perpendicular to the coast.<ref name=Davis/><ref>{{cite encyclopedia |year=1990 |title=Lagoon |encyclopedia=Oxford Dictionary of Earth Sciences |publisher=Oxford University Press |location=Oxford |editor=Allaby, Michael |isbn=978-0-19-921194-4}}</ref><ref name=Kusky>{{cite encyclopedia |editor=Kusky, Timothy |encyclopedia=Encyclopedia of Earth Sciences |title=Lagoon |url=https://archive.org/details/encyclopediaofea0000kusk/page/245 |year=2005 |publisher=Facts on File |location=New York |isbn=0-8160-4973-4 |page=[https://archive.org/details/encyclopediaofea0000kusk/page/245 245] }}</ref><ref name=Nybakken>{{cite encyclopedia |editor=Nybakken, James W. |encyclopedia=Interdisciplinary Encyclopedia of Marine Sciences |title=Lagoon |year=2003 |publisher=Grolier Academic Reference |volume=2 G-O |location=Danbury, Connecticut |isbn=0-7172-5946-3 |pages=189–90}}</ref><ref>{{Cite book | author=Reid, George K.| title=Ecology of Inland Waters and Estuaries| url=https://archive.org/details/ecologyofinlandw0000reid_r5j1| url-access=registration| publisher=Van Nostrand Reinhold Company|location=New York| year=1961|page=[https://archive.org/details/ecologyofinlandw0000reid_r5j1/page/74 74] |asin=B003MRW6AK}}</ref> Coastal lagoons are classified as inland bodies of water.<ref>{{cite book|page=263|url=https://books.google.com/books?id=VWnxpAxp6TMC|title=Encyclopedia of coastal science|author=Maurice L. Schwartz|publisher=Springer|year=2005|isbn=978-1-4020-1903-6|access-date=31 March 2012}}</ref><ref>{{cite book|pages=1–3|url=https://books.google.com/books?id=MrwTtP0mLjUC|title=Coastal lagoon processes|first=Björn |last=Kjerfve |publisher=Elsevier|year=1994|isbn=978-0-444-88258-5|chapter=Coastal Lagoons}}</ref>

When used within the context of a distinctive portion of coral reef [[ecosystems]], the term "lagoon" is synonymous with the term "back reef" or "backreef", which is more commonly used by coral reef scientists to refer to the same area.<ref>{{Cite journal | last1 = Aronson | first1 = R. B. | title = Hurricane effects on backreef echinoderms of the Caribbean | doi = 10.1007/BF00334473 | journal = Coral Reefs | volume = 12 | issue = 3–4 | pages = 139–142 | year = 1993 | bibcode = 1993CorRe..12..139A | s2cid = 879073 }}</ref>

Many lagoons do not include "lagoon" in their common names. [[Currituck Sound|Currituck]], [[Albemarle Sound|Albemarle]] and [[Pamlico Sound|Pamlico]] Sounds in [[North Carolina]],<ref>{{cite journal |last=Jia |first=Peng and Ming Li |year=2012 |title=Circulation dynamics and salt balance in a lagoonal estuary |url=http://www.agu.org/pubs/crossref/2012/2011JC007124.shtml |journal=Journal of Geophysical Research: Oceans |volume=117 |issue=C01003 |pages=C01003 |bibcode=2012JGRC..117.1003J |doi=10.1029/2011JC007124 |archive-url=https://web.archive.org/web/20140819170946/http://onlinelibrary.wiley.com/doi/10.1029/2011JC007124/abstract |archive-date=Aug 19, 2014 |access-date=24 March 2012 |doi-access=free}}</ref> [[Great South Bay]] between [[Long Island]] and the barrier beaches of [[Fire Island, New York|Fire Island]] in [[New York (state)|New York]],<ref>{{cite web|last=Goodbred|first=S. Jr., P. Locicero, V. Bonvento, S. Kolbe, S. Holsinger|title=History of the Great South Bay estuary:Evidence of a catastrophic origin|url=http://dspace.sunyconnect.suny.edu/bitstream/handle/1951/48052/goodbred.pdf;jsessionid=92152E84183F75FD0A4D6181D902AEFE?sequence=1|publisher=State University of New York|access-date=24 March 2012}}</ref> [[Isle of Wight Bay]], which separates [[Ocean City, Maryland]] from the rest of [[Worcester County, Maryland]],<ref>{{cite journal|last=Boynton|first=W. R., J. D. Hagy, L. Murray, C. Stokes, W. M Kemp|title=A Comparative Analysis of Eutrophication Patterns in a Temperate Coastal Lagoon|journal=Estuaries|date=June 1996|volume=19|issue=2B|pages=408–421|url=http://www.gonzo.cbl.umces.edu/documents/water_quality/Est19_408.pdf|access-date=24 March 2012|doi=10.2307/1352459|jstor=1352459|s2cid=14978943}}</ref> [[Banana River]] in [[Florida]], US,<ref>{{cite web |title=Total Maximum Daily Loads for the North and Central Indian River Lagoon and Banana river Lagoon, Florida |url=http://www.epa.gov/waters/tmdldocs/6Final_IRL_NutriDO_TMDLs0407.pdf |archive-url=https://web.archive.org/web/20150924143849/http://www.epa.gov/waters/tmdldocs/6Final_IRL_NutriDO_TMDLs0407.pdf |archive-date=24 September 2015 |access-date=24 March 2012 |publisher=United States Environmental Protection Agency}}</ref> [[Lake Illawarra]] in [[New South Wales]], Australia,<ref>{{cite web|title=Proposed Swimming Enclosure Net, Entrance Lagoon, Lake Illawarra|url=http://www.lia.nsw.gov.au/pdf/studies/Enclosure_Net_REF.pdf|publisher=Lake Illawarra Authority|access-date=24 March 2012|archive-url=https://web.archive.org/web/20110228025307/http://www.lia.nsw.gov.au/pdf/studies/Enclosure_Net_REF.pdf|archive-date=28 February 2011}}</ref> [[Montrose Basin]] in [[Scotland]],<ref>{{cite book|last=Bird|first=Eric C. F.|title=Encyclopedia of the World's Coastal Landforms| volume=1|year=2010|publisher=Springer|location=Dordrecht|isbn=978-1-4020-8638-0|page=485|url=https://books.google.com/books?id=Mfo5TPb7SDsC&q=montrose+basin+lagoon&pg=PA485}}</ref> and [[Broad Water]] in [[Wales]] have all been classified as lagoons, despite their names. In England, [[Chesil Beach#The Fleet|The Fleet]] at Chesil Beach has also been described as a lagoon.

In some languages the word for a lagoon is simply a type of lake: In Chinese a lake is ''{{Lang|zh-latn|hu}}'' ({{Lang|zh|湖|italic=no}}), and a lagoon is ''{{Lang|zh-latn|xihu}}'' ({{Lang|zh|潟湖|italic=no}}). In the [[France|French]] Mediterranean several lagoons are called ''étang'' ("lake"). Contrariwise, several other languages have specific words for such bodies of water. In Spanish, coastal lagoons generically are ''{{Lang|es|laguna costera}}'', but those on the Mediterranean coast are specifically called ''{{Lang|es|[[albufera]]}}''. In Russian and Ukrainian, those on the [[Black Sea]] are ''{{Lang|ru-latn|[[Liman (landform)|liman]]}}'' ({{Lang|ru|лиман|italic=no}}), while the generic word is ''{{Lang|uk-latn|laguna}}'' ({{Lang|uk|Лагуна|italic=no}}). Similarly, in the [[Baltic Sea|Baltic]], Danish has the specific ''{{Lang|da|{{ill|Nor (landform)|lt=Nor|da|Nor}}}}'', and German the specifics ''{{Lang|de|[[Bodden]]}}'' and ''[[Haff (lagoon)|Haff]]'', as well as generic terms derived from ''{{Lang|de|laguna}}''. In Poland these lagoons are called ''zalew'' ("bay"), and in Lithuania ''marios'' ("lagoon, reservoir"). In [[Jutland]] several lagoons are known as ''[[fjord]]''. In [[New Zealand]] the [[Māori language|Māori]] word ''{{Lang|mi|[[hapua]]}}'' refers to a coastal lagoon formed at the mouth of a [[braided river]] where there are mixed sand and gravel beaches, while {{Lang|mi|[[waituna]]}}, an [[ephemeral]] coastal waterbody, is neither a true lagoon, lake, nor estuary.<ref>{{Cite book |last=Kirk, R.M. and Lauder, G.A |title=Significant coastal lagoon systems in the South Island, New Zealand: coastal processes and lagoon mouth closure |publisher=[[Department of Conservation (New Zealand)|Department of Conservation]] |year=2000 |isbn=0-478-21947-4 |location=Wellington, N.Z.}}</ref>

Some languages differentiate between coastal and atoll lagoons. In French, ''{{Lang|fr|{{ill|lagon (French)|lt=lagon|fr|lagon}}}}'' refers specifically to an atoll lagoon, while coastal lagoons are described as {{Lang|fr|{{ill|étang|fr}}}}, the generic word for a still lake or pond.
In Vietnamese, ''{{Lang|vi|Đầm san hô}}'' refers to an atoll lagoon, whilst ''{{Lang|vi|Đầm phá}}'' is coastal.

In Latin America, the term ''{{Lang|es|laguna}}'' in Spanish, which lagoon translates to, may be used for a small fresh water [[lake]] in a similar way a [[Stream|creek]] is considered a small river. However, sometimes it is popularly used to describe a full-sized [[lake]], such as [[Laguna Catemaco]] in Mexico, which is actually the third-largest lake by area in the country. The [[brackish water]] lagoon may be thus explicitly identified as a "coastal lagoon" (''{{Lang|es|laguna costera}}''). In Portuguese, a similar usage is found: ''{{Lang|pt|lagoa}}'' may be a body of shallow seawater, or a small freshwater lake not linked to the sea.

===Etymology===
Lagoon is derived from the [[Italian language|Italian]] ''{{lang|it|laguna}}'', which refers to the waters around [[Venice]], the [[Lagoon of Venice|Venetian Lagoon]]. ''Laguna'' is attested in English by at least 1612, and had been [[Anglicisation|Anglicized]] to "lagune" by 1673. In 1697 [[William Dampier]] referred to a "Lagune or Lake of Salt water" on the coast of Mexico. [[James Cook|Captain James Cook]] described an island "of Oval form with a Lagoon in the middle" in 1769.<ref>{{cite encyclopedia |encyclopedia=Oxford English Dictionary |title=Lagoon |edition=Compact |year=1971 |publisher=Oxford University Press |volume=I A-O |location=Oxford, England |page=1560 }}</ref>

==Atoll lagoons==
{{further|List of largest atolls}}
[[File:Atafutrim.jpg|thumb|Satellite picture of the [[Atafu]] atoll in [[Tokelau]] in the [[Pacific Ocean]]]]
[[Atoll]] lagoons form as coral reefs grow upwards while the islands that the reefs surround subside, until eventually only the reefs remain above sea level. Unlike the lagoons that form shoreward of fringing reefs, atoll lagoons often contain some deep (>{{Convert|20|m|ft|abbr=on}}) portions.{{citation needed|date=March 2025}}

==Coastal lagoons==
[[File:Caspian Sea covered with plants near Bandar-e Anzali - Barry Kent.jpg|thumb|[[Anzali Lagoon]] in southwestern [[Caspian Sea]] coast, [[Iran]]]]
[[File:Hiddensee (2011-05-21).JPG|thumb|Coastal lagoon landscapes around the island of [[Hiddensee]] near [[Stralsund]], [[Germany]]. Many similar coastal lagoons can be found around the [[Western Pomerania Lagoon Area National Park]].]]

Coastal lagoons form along gently sloping coasts where barrier islands or reefs can develop offshore, and the sea-level is rising relative to the land along the shore (either because of an intrinsic rise in sea-level, or [[subsidence]] of the land along the coast). Coastal lagoons do not form along steep or rocky coasts, or if the range of tides is more than {{convert|4|m|ft}}. Due to the gentle slope of the coast, coastal lagoons are shallow. A relative drop in sea level may leave a lagoon largely dry, while a rise in sea level may let the sea breach or destroy barrier islands, and leave reefs too deep underwater to protect the lagoon. Coastal lagoons are young and dynamic, and may be short-lived in geological terms. Coastal lagoons are common, occurring along nearly 15 percent of the world's shorelines. In the United States, lagoons are found along more than 75 percent of the [[East Coast of the United States|Eastern]] and [[Gulf Coast of the United States|Gulf Coasts]].<ref name=Kusky/><ref name=Nybakken/>

Coastal lagoons can be classified as leaky, restricted, or choked.<ref name=Kjerfve1986>{{cite book | last=Kjerfve | first=Björn | author-link=Björn Kjerfve | title=Estuarine Variability | chapter=Comparative oceanography of coastal lagoons | publisher=Elsevier | year=1986 | isbn=978-0-12-761890-6 | doi=10.1016/b978-0-12-761890-6.50009-5 | pages=63–81}}</ref>
Coastal lagoons are usually connected to the open ocean by [[inlet]]s between barrier islands. The number and size of the inlets, precipitation, evaporation, and inflow of fresh water all affect the nature of the lagoon. Lagoons with little or no interchange with the open ocean, little or no inflow of fresh water, and high evaporation rates, such as [[Lake St. Lucia]], in [[South Africa]], may become highly saline. Lagoons with no connection to the open ocean and significant inflow of fresh water, such as the [[Lake Worth Lagoon#History|Lake Worth Lagoon]] in Florida in the middle of the 19th century, may be entirely fresh. On the other hand, lagoons with many wide inlets, such as the [[Wadden Sea]], have strong tidal currents and mixing. Coastal lagoons tend to accumulate sediments from inflowing rivers, from runoff from the shores of the lagoon, and from sediment carried into the lagoon through inlets by the tide. Large quantities of sediment may be occasionally be deposited in a lagoon when storm waves overwash barrier islands. [[Mangrove]]s and [[Salt marsh|marsh]] plants can facilitate the accumulation of sediment in a lagoon. [[Benthos|Benthic organisms]] may stabilize or destabilize sediments.<ref name=Kusky/><ref name=Nybakken/> 

=== Largest coastal lagoons ===
{{Cleanup list|section|date=October 2023}}
{{redirect-distinguish|List of largest lagoons|List of largest atoll lagoons}}

{| class="wikitable"

|-
! Lagoon!! Area  !!Country
|-
|[[New Caledonian lagoon]]|| {{Convert|24,000|km2|sqmi|abbr=on|sp=us}}||{{country|New Caledonia}}
|-
|[[Garabogazköl]]|| {{Convert|18,000|km2|sqmi|abbr=on|sp=us}}||{{country|Turkmenistan}} 
|-
|[[Lake Maracaibo]]|| {{convert|13512|km2|sqmi|abbr=on}}||{{country|Venezuela}}
|-
|{{Lang|pt|[[Lagoa dos Patos]]|italic=no}}{{efn|The largest choked coastal lagoon.<ref name=Kjerfve1986/>}} || {{Convert|10,100|km2|sqmi|abbr=on|sp=us|sigfig=1}}||{{country|Brazil}}
|-
|[[Albemarle Sound|Albemarle]]-[[Pamlico Sound|Pamlico]] sound system|| {{Convert|3000|sqmi|km2|abbr=on|order=flip}}||{{country|United States}}
|-
|[[Lagos Lagoon]]|| {{convert|6354.7|km2|sqmi|abbr=on}}||{{country|Nigeria}}
|-
|[[Curonian lagoon]]|| {{Convert|1,619|km2|sqmi|abbr=on|sp=us}}||{{country|Lithuania}} /{{country|Russia}}
|-
|[[Mayotte lagoon]]|| ~{{Convert|1,500|km2|sqmi|abbr=on|sp=us|sigfig=1}}||{{country|France}}
|-
|[[Rangiroa lagoon]]|| {{Convert|1,446|km2|sqmi|abbr=on|sp=us|sigfig=1}}||{{country|French Polynesia}}
|-
|[[Chilika Lake]]|| {{Convert|1165|km2|sqmi|abbr=on}} during monsoon season, {{Convert|906|km2|sqmi|abbr=on}} during dry season||{{country|India}}
|-
|-
|[[Caratasca Lagoon]]|| {{Convert|1110|km2|sqmi|abbr=on}} ||{{country|Honduras}}
|-
|[[Indian River Lagoon]]|| {{Convert|353|sqmi|km2|abbr=on|order=flip}}<ref>{{Cite web |date=2024 |title=Fast facts about the Indian River Lagoon |url=https://www.sjrwmd.com/waterways/indian-river-lagoon/facts/ |access-date=12 July 2024 |website=St. Johns River Water Management District}}</ref>||{{country|United States}}
|-
|[[Vistula lagoon]]|| {{Convert|838|km2|sqmi|abbr=on|sp=us}}||{{country| Russia}} /{{country|Poland}}
|-
|[[Biscayne Bay]] System<br />—Biscayne Bay (traditional)|| {{Convert|703|km2|sqmi|abbr=on}}<ref>{{Cite journal|last=Smith|first=Ned P.|date=Summer 2001|title=Tides of Biscayne Bay, Card Sound, Little Card Sound, Barnes Sound, and Manatee Bay, Florida|journal=Florida Scientist|volume=64|page=224|jstor=24321024}}</ref><br />{{Convert|572|km2|sqmi|abbr=on}}<ref>{{Cite report|last=Milano|first=Gary R.|title=Island Restoration and Enhancement in Biscayne Bay, Florida|date=2000|url=https://www.miamidade.gov/environment/library/reports/island-restoration.pdf|access-date=April 21, 2021|website=Miami-Dade Department of Environmental Resources Management|section=Introduction}}</ref>
||{{country|United States}} 
|-
|[[Marovo lagoon]]|| {{Convert|700|km2|sqmi|abbr=on|sp=us|sigfig=3}}||{{country|Solomon Islands}}
|-
|[[Szczecin Lagoon]] || {{convert|689|km2|sqmi|abbr=on}}||{{country|Germany}} / {{country|Poland}}
|-
|[[Venetian Lagoon]]|| {{Convert|550|km2|sqmi|abbr=on|sp=us}}||{{country|Italy}}
|}

==Images==

{{gallery
|title=
|width=240
|height=200
|align=center
|File:Lagoa_dos_Patos_PIA03444_lrg.jpg|{{Lang|pt|[[Lagoa dos Patos]]|italic=no}}, the largest lagoon in South America, in the [[States_of_Brazil|Brazilian state]] of [[Rio Grande do Sul]].|Image:Boraboraluft gerade.jpg|Aerial view of [[Bora Bora]] in [[French Polynesia]].
|Image:Kivalina Alaska aerial view.jpg|Aerial view of [[Kivalina, Alaska]] from the northwest.
|Image:Kiritimati-EO.jpg|Nearly half the area of [[Kiritimati]] is covered with lagoons, some freshwater and some seawater.
|Image:Blue Lagoon,Nusa Lembongan-Bali.jpg|Nusa Lembongan Lagoon, [[Bali]], [[Indonesia]].
|File:LEFKADA Panorama1.jpg|Panoramic view of Lefkada City Lagoon, Lefkada Isl., [[Ionian Islands]] Prefecture, [[Greece]].
|File:KALOGRIA Panorama.jpg|Panoramic view of Prokopos Lagoon, [[Achaia]], Western Greece Prefecture, Greece.
|File:Island lagoon in Bacuit Bay, El Nido, Palawan, Philippines.jpg|Tropical lagoon in Bacuit Bay, Palawan, Philippines.
|File:Cartagena, Mar Menor, i Cap de Pals (foto satèl·lit).jpg|Photo of [[Mar Menor]] as seen from International Space Station.
}}

==See also==
{{Portal|Wetlands}}
{{col div|colwidth=30em}}
* [[Aerated lagoon]]
* [[Anaerobic lagoon]]
* [[Ayre (landform)]]
* [[Barachois]]
* [[Braided river]]
* [[Estuary]]
* [[Haff (lagoon)|Haff (estuarine lagoon)]]
* [[Longshore drift]]
* [[Sediment transport]]
{{colend}}

==Notes==
{{Notelist}}

==References==
{{Reflist}}

{{Wikiquote}}
{{Commons category|Lagoons}}

{{aquatic ecosystem topics|expanded=marine}}
{{coastal geography}}

{{Authority control}}

[[Category:Lagoons| ]]
[[Category:Coastal and oceanic landforms]]
[[Category:Oceanographical terminology]]
[[Category:Bodies of water]]