A ria (; gl, ría) is a coastal

inlet An inlet is a (usually long and narrow) indentation of a shoreline, such as a small arm, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea. Overview In marine geogra ...

formed by the partial submergence of an unglaciated

river valley A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...

. It is a drowned river valley that remains open to the sea.

Definitions

Typically rias have a

dendritic Dendrite derives from the Greek word "dendron" meaning ( "tree-like"), and may refer to: Biology *Dendrite, a branched projection of a neuron *Dendrite (non-neuronal), branching projections of certain skin cells and immune cells Physical * Dendr ...

, treelike outline although they can be straight and without significant branches. This pattern is inherited from the dendritic drainage pattern of the flooded river valley. The drowning of river valleys along a stretch of coast and formation of rias results in an extremely irregular and indented coastline. Often, there are naturally occurring islands, which are summits of partly submerged, pre-existing hill peaks. (Islands may also be artificial, such as those constructed for the

Chesapeake Bay Bridge-Tunnel Chesapeake often refers to: *Chesapeake people, a Native American tribe also known as the Chesepian * The Chesapeake, a.k.a. Chesapeake Bay *Delmarva Peninsula, also known as the Chesapeake Peninsula Chesapeake may also refer to: Populated plac ...

.) A ria coast is a coastline having several parallel rias separated by prominent ridges, extending a distance inland.Goudie, A. (2004) ''Encyclopedia of Geomorphology.'' Routledge. London, England.Bird, E.C.F. (2008) ''Coastal Geomorphology: An Introduction'', 2nd ed. John Wiley and Sons Ltd. West Sussex, England. The sea level change that caused the submergence of a river valley may be either

eustatic Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...

(where global sea levels rise), or isostatic (where the local land sinks). The result is often a very large

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

at the mouth of a relatively insignificant river (or else sediments would quickly fill the ria). The

Kingsbridge Estuary The Kingsbridge Estuary (also, erroneously, known as the 'Salcombe Estuary') in the South Hams area of Devon, England runs from Kingsbridge in the north to its mouth at the English Channel near Salcombe and lies between Bolt Head and Sharpitor t ...

Devon Devon ( , historically known as Devonshire , ) is a ceremonial and non-metropolitan county in South West England. The most populous settlement in Devon is the city of Plymouth, followed by Devon's county town, the city of Exeter. Devon is ...

, England, is an extreme example of a ria forming an estuary disproportionate to the size of its river; no significant river flows into it at all, only a number of small streams. The word ''

ria A ria (; gl, ría) is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea. Definitions Typically rias have a dendritic, treelike outline although they ca ...

'' comes from Galician ''

ría A ria (; gl, ría) is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea. Definitions Typically rias have a dendritic, treelike outline although they c ...

'', which is related to Spanish and Galician '' río'' and Portuguese ''

rio Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...

'' (river). Rias are present all along the Galician coast in

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

. As originally defined, the term was restricted to drowned river valleys cut parallel to the structure of the

country rock Country rock is a genre of music which fuses rock and country. It was developed by rock musicians who began to record country-flavored records in the late 1960s and early 1970s. These musicians recorded rock records using country themes, vocal s ...

that was at right angles to the coastline. However the definition of ria was later expanded to other flooded river valleys regardless of the structure of the country rock. For a time European geomorphologists considered rias to include any broad estuarine river mouth, including

fjord In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Ice ...

s. These are long narrow

s with steep sides or cliffs, created in a valley carved by glacial activity. In the 21st century, however, the preferred usage of ''ria'' by geologists and geomorphologists is to refer solely to drowned unglaciated river valleys. It therefore excludes fjords by definition, since fjords are products of glaciation.

Locations

Europe

Pogled s Golubova kamena na Rijeku dubrovačku

* Portugal: has no ''rias'' as such: the

Ria de Aveiro The Aveiro lagoon (''Ria de Aveiro'') is a lagoon in Portugal. It is located on the Atlantic coast of Portugal, south of the municipality of Espinho and north of Mira (to the north of the Cape Mondego). Its average area covers approximately . It ...

in Aveiro, and

Ria Formosa The Ria Formosa lagoon, located in the Algarve, in southern Portugal, is a system of barrier islands that connects to the sea through six inlets. Five of these inlets are natural and have mobility characteristics. The sixth is an artificial inlet ...

in Eastern

Algarve The Algarve (, , ; from ) is the southernmost NUTS II region of continental Portugal. It has an area of with 467,495 permanent inhabitants and incorporates 16 municipalities ( ''concelhos'' or ''municípios'' in Portuguese). The region has it ...

are actually

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

s. * Atlantic coast of Spain ** Galicia: *** The

Rías Baixas The Rías Baixas ( Galician for "Lower Rias") are a series of four estuarine inlets located on the southwestern coast of Galicia, Spain. They are the Ría de Muros e Noia, the Ría de Arousa, the Ría de Pontevedra, and the Ría de Vigo.Mendez ...

, including the Ria of

Vigo Vigo ( , , , ) is a city and Municipalities in Spain, municipality in the province of Pontevedra, within the Autonomous communities of Spain, autonomous community of Galicia (Spain), Galicia, Spain. Located in the northwest of the Iberian Penins ...

, Ria of

Pontevedra Pontevedra (, ) is a Spanish city in the north-west of the Iberian Peninsula. It is the capital of both the ''Comarca'' (County) and Province of Pontevedra, and of the Rías Baixas in Galicia. It is also the capital of its own municipality whi ...

Ría de Arousa The ''Ría de Arousa'' is a ria, a saline estuary, that forms a firth situated on Galicia, Spain. It is one of the five ''Rías Baixas''. The Ría de Arousa estuary is the largest of the estuaries of Galicia. It is part of the Rias Baixas and is ...

, Ria of

Muros Muros may refer to: *Muros, A Coruña, a municipality in the province of A Coruña in the autonomous community of Galicia, Spain * Muros, Sardinia, a comune in the province of Sassari in the region Sardini, Italy * Muros (comarca), a comarca in the ...

and

Noia Noia () is a town and municipality in the autonomous community of Galicia in northwestern Spain. It is the capital of the comarca with the same name. It has a population of 14,947 inhabitants (2010),Corcubion, Cee and Ría de Aldán. *** The

Rías Altas Rías Altas (also called "Upper Rias") is the northernmost of three sections of '' A Costa do Marisco'' (the Seafood Coast) in Galicia, Spain. It extends from the port of Ribadeo to Santa Cruz. The Upper Rias refers to the coast of the northern ...

, including the Ria of Corunna, Ria of

Ares Ares (; grc, Ἄρης, ''Árēs'' ) is the Greek god of war and courage. He is one of the Twelve Olympians, and the son of Zeus and Hera. The Greeks were ambivalent towards him. He embodies the physical valor necessary for success in war b ...

and

Betanzos Betanzos () is a municipality in the autonomous community of Galicia in northwestern Spain in the province of A Coruña. It belongs to the comarca of Betanzos. In Roman times Betanzos was called Flauvium Brigantium or ''Brigantium''. During the ...

, Ria of

Cedeira Cedeira is a municipality in the province of A Coruña in the autonomous community of Galicia in northwestern Spain. It is situated in the northern coast of the Rías Altas. Cedeira has a population of 7,412 inhabitants (INE, 2010). Parroquias * ...

, Ria of

O Barqueiro O Barqueiro (also Port of El Barquero) is a parish and a port belonging to the city council of Mañón in Ferrolterra in North-western Spain in the province of A Coruña, in the autonomous community of Galicia. Industry * Important fishing ...

Ria of Ferrol The Ria of Ferrol (or bay of Ferrol; Spanish language, Spanish and Galician language, Galician: ''ría de Ferrol'') is a ria in Galicia, Spain, Galicia, Spain, the saline estuary of the Xuvia River. Located in the province of A Coruña, in the nor ...

, Ria of

Ortigueira Ortigueira is a seaport and municipality in the province of A Coruña (province), A Coruña the autonomous community of Galicia, Spain, Galicia in northwestern Spain. It belongs to the Comarcas of Galicia, comarca of Ortegal. It is located on th ...

, Ria of

Viveiro Viveiro () is a town and municipality in the province of Lugo, in the northwestern Galician autonomous community of Spain. It borders on the Cantabric Sea, to the west of Xove and to the east of O Vicedo. It has a residential population of o ...

, Ria of

Foz Foz () is a town and municipality in the A Mariña Central comarca in the Galician province of Lugo. It has been historically linked to the Ancient Province of Mondoñedo and also linked to the arrival of Briton immigrants during the Dark Age ...

and Ria of

Ribadeo Ribadeo is a municipality in the Spanish province of Lugo in Galicia. It has a population of 10,023 (INE, 2011) and an area of . It is the capital of the A Mariña Oriental comarca. Geography The municipality of Ribadeo has approximately the ...

. **

Asturias Asturias (, ; ast, Asturies ), officially the Principality of Asturias ( es, Principado de Asturias; ast, Principáu d'Asturies; Galician-Asturian: ''Principao d'Asturias''), is an autonomous communities of Spain, autonomous community in nor ...

: Ria of

Avilés Avilés (; ) is a town in Asturias, Spain. Avilés is, along with Oviedo and Gijón, one of the main cities in the Principality of Asturias. The town occupies the flattest land in the municipality, partially in a land that belonged to the sea, ...

, Ria of

, Ria of Navia, Ria of Villaviciosa, Ria of

Ribadesella Ribadesella (Asturian: Ribeseya) is a small municipality in the Autonomous Community of the Principality of Asturias, Spain. Known for its location on the Cantabrian Sea, at the outlet of the River Sella, Ribadesella is a town that forms part ...

, Ria of

Llanes Llanes (the ''Concejo de Llanes'', ''Conceyu de Llanes'' in Asturian language) is a municipality of the province of Asturias, in northern Spain. Stretching for about 30 km along the coast at the extreme east of the province, Llanes is bound ...

, Ria of Tina Mayor. **

Cantabria Cantabria (, also , , Cantabrian: ) is an autonomous community in northern Spain with Santander as its capital city. It is called a ''comunidad histórica'', a historic community, in its current Statute of Autonomy. It is bordered on the east ...

: Ria of Tina Mayor, Ria of Tina Menor, Ría de

San Vicente de la Barquera San Vicente de la Barquera is a municipality of Cantabria in northern Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English ...

, Ría of la Rabia, Ría of San Martín de la Arena, Ría of Mogro, Ría of Solía, Ría of Carmen, Ría of Boo, Ría of Tijero, Ría of Cubas, Ría de Ajo, Ría of Cabo Quejo, Ría of Treto, Ría of Oriñón. ** Basque Country: Ria of Bilbao, mouth of the rivers

Nervión , name_etymology = , image = Nervion.jpg , image_size = 300px , image_caption = River Nervion with Zubizuri footbridge. , map = , map_size = , map_caption = , pushpin_map ...

Ibaizabal The Ibaizabal (''wide river'' in Basque) is a river that drains southeastern Biscay to the Estuary of Bilbao. It is long from its source at Elorrio to the Nervión, and it passes by the towns of Durango and Amorebieta and joins the Nervión rive ...

, and

Cadagua The Cadagua or Kadagua River drains the Biscayan area of Encartaciones (), from the Castilian valley of Mena to Barakaldo and Bilbao, where it forms the border between these municipalities and ends at the Estuary of Bilbao The Estuary of Bilba ...

. **

Andalusia Andalusia (, ; es, Andalucía ) is the southernmost Autonomous communities of Spain, autonomous community in Peninsular Spain. It is the most populous and the second-largest autonomous community in the country. It is officially recognised as a ...

: Ria of Carreras, Ria of

Huelva Huelva (, ) is a city in southwestern Spain, the capital of the province of Huelva in the autonomous community of Andalusia. It is between two short rias though has an outlying spur including nature reserve on the Gulf of Cádiz coast. The rias ...

at the mouth of the rivers

Odiel The Odiel ( es, Río Odiel) is a river in the Atlantic basin in southern Spain, more precisely in the province of Huelva, Andalusia. It originates at Marimateos in the Sierra de Aracena at an elevation of above sea level. At the Punta del Seb ...

and

Tinto Tinto is an isolated hill in the Southern Uplands of Scotland. It comprises little more than one top, which stands on the west bank of the River Clyde, some west of Biggar. The peak is also called "Tinto Tap", with the name Tinto possibly de ...

. * Brittany: The rias in northern Brittany are called ''Abers'': ''

Aber Wrac'h The Aber Wrac'h is a small village and port located on the river Wrac'h in the commune of Landéda in the department of Finistère in France, located in Brittany. The Wrac'h's source is in Trémaouézan. It travels through Ploudaniel, Le Folg ...

'' (), ''Aber Benoît'' (), ''Aber Ildut'' () etc. The

Roadstead of Brest The roadstead of Brest (''rade de Brest'') is a roadstead or bay located in the Finistère Departments of France, department in Brittany (administrative region), Brittany in northwestern France. The surface area is about 180 km² (70 sq ...

also includes several rias. * Ireland:

Bantry Bay Bantry Bay ( ga, Cuan Baoi / Inbhear na mBárc / Bádh Bheanntraighe) is a bay located in County Cork, Ireland. The bay runs approximately from northeast to southwest into the Atlantic Ocean. It is approximately 3-to-4 km (1.8-to-2.5 mil ...

, on the southwest coast of Ireland, is an example of an Irish ria. * Wales:

Milford Haven Waterway Milford Haven Waterway (''Welsh: Dyfrffordd Aberdaugleddau'') is a natural harbour in Pembrokeshire, Wales. It is a ria or drowned valley which was flooded at the end of the last ice age. The Daugleddau estuary winds west to the sea. As on ...

Pembrokeshire Pembrokeshire ( ; cy, Sir Benfro ) is a Local government in Wales#Principal areas, county in the South West Wales, south-west of Wales. It is bordered by Carmarthenshire to the east, Ceredigion to the northeast, and the rest by sea. The count ...

is a ria. * England: The south coast of England is a

submergent coastline Submergent coastlines or drowned coastlines are stretches along the coast that have been inundated by the sea by a relative rise in sea levels from either isostacy or eustacy. Submergent coastline are the opposite of emergent coastlines, whic ...

which contains many rias, including

Southampton Water Southampton Water is a tidal estuary north of the Solent and the Isle of Wight in England. The city of Southampton lies at its most northerly point, where the estuaries of the River Test and River Itchen meet. Along its salt marsh-fringed wes ...

Poole Harbour Poole Harbour is a large natural harbour in Dorset, southern England, with the town of Poole on its shores. The harbour is a drowned valley (ria) formed at the end of the last ice age and is the estuary of several rivers, the largest being th ...

, the estuary of the

River Medina The River Medina is the main river of the Isle of Wight, England, rising at St Catherine's Down near Chale, and flowing northwards through the county town Newport, towards the Solent at Cowes. The river is a navigable tidal estuary from Newpor ...

on the Isle of Wight, the estuaries of the

Exe Exe or EXE may refer to: * .exe, a file extension * exe., abbreviation for executive Places * River Exe, in England * Exe Estuary, in England * Exe Island, in Exeter, England Transportation and vehicles * Exe (locomotive), a British locomotive ...

Teign Teigne (also : Teign, Tègne, Teeñ, Tin or Tañ in Wolof language) was the title of the monarch of the pre-colonial Kingdom of Baol, now part of present-day Senegal. In Wolof, "Teigne" means the support that is placed on the head to carry so ...

and

Dart Dart or DART may refer to: * Dart, the equipment in the game of darts Arts, entertainment and media * Dart (comics), an Image Comics superhero * Dart, a character from ''G.I. Joe'' * Dart, a ''Thomas & Friends'' railway engine character * Dar ...

, then

Plymouth Sound Plymouth Sound, or locally just The Sound, is a deep inlet or sound in the English Channel near Plymouth in England. Description Its southwest and southeast corners are Penlee Point in Cornwall and Wembury Point in Devon, a distance of abo ...

, and the estuaries of the

River Fowey The River Fowey ( ; kw, Fowi) is a river in Cornwall, England, United Kingdom. It rises at Fowey Well (originally kw, Fenten Fowi, meaning ''spring of the river Fowey'') about north-west of Brown Willy on Bodmin Moor, not far from one of i ...

River Fal The River Fal ( kw, Dowr Fala) flows through Cornwall, England, rising at Pentevale on Goss Moor (between St. Columb and Roche) and reaching the English Channel at Falmouth. On or near the banks of the Fal are the castles of Pendennis and ...

and

Helford River The Helford River ( kw, Dowr Mahonyer) is a ria (flooded river valley) in Cornwall, England, fed by small streams into its many creeks. There are seven creeks on the Helford; from west to east these are Ponsontuel Creek, Mawgan Creek, Polpenwit ...

Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...

. On the north coast is the

River Camel The River Camel ( kw, Dowr Kammel, meaning ''crooked river'') is a river in Cornwall, England. It rises on the edge of Bodmin Moor and with its tributaries its catchment area covers much of North Cornwall. The river flows into the eastern Cel ...

and the

River Taw The River Taw () rises at Taw Head, a spring on the central northern flanks of Dartmoor, crosses North Devon and at the town of Barnstaple, formerly a significant port, empties into Bideford Bay in the Bristol Channel, having formed a large ...

. In

Essex Essex () is a county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, and G ...

are the River Blackwater and

River Crouch The River Crouch is a small river that flows entirely through the English county of Essex. The distance of the Navigation between Holliwell Point which is north of Foulness Island and Battlesbridge is 17.5 Miles, i.e. 15.21 Nautical Miles. Ro ...

. * Croatia: Lim,

Rijeka Dubrovačka Rijeka Dubrovačka (Italian: ''Val d'Ombla'') is a ria (coastal inlet) to the north of Dubrovnik, Croatia, on the coast of the Adriatic Sea. The Ombla The Ombla is a short river in Croatia, northeast of Dubrovnik. Its course is approximately lo ...

* Montenegro: The

Bay of Kotor The Bay of Kotor ( Montenegrin and Serbian: , Italian: ), also known as the Boka, is a winding bay of the Adriatic Sea in southwestern Montenegro and the region of Montenegro concentrated around the bay. It is also the southernmost part of the hi ...

* Italy: The

Fiordo di Furore Furore is a town and ''comune'' in the province of Salerno in the Campania region of south-western Italy. Furore is located on the Amalfi Coast. Geography The municipality of Furore expands from sea level, where there is the hamlet of Fiordo di F ...

on the

Amalfi Coast The Amalfi Coast ( it, Costiera amalfitana) is a stretch of coastline in southern Italy overlooking the Tyrrhenian Sea and the Gulf of Salerno. It is located south of the Sorrentine Peninsula and north of the Cilentan Coast. Celebrated worldwide ...

Campania Campania (, also , , , ) is an administrative Regions of Italy, region of Italy; most of it is in the south-western portion of the Italian peninsula (with the Tyrrhenian Sea to its west), but it also includes the small Phlegraean Islands and the i ...

is a ria, despite its name. * Malta:

Grand Harbour The Grand Harbour ( mt, il-Port il-Kbir; it, Porto Grande), also known as the Port of Valletta, is a natural harbour on the island of Malta. It has been substantially modified over the years with extensive docks (Malta Dockyard), wharves, and ...

and

Marsamxett Harbour Marsamxett Harbour (), historically also referred to as Marsamuscetto, is a natural harbour on the island of Malta. It is located to the north of the larger Grand Harbour. The harbour is generally more dedicated to leisure use than the Grand Ha ...

Africa

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

Kilindini Harbour Kilindini Harbour is a large, natural deep-water inlet extending inland from Mombasa, Kenya. It is at its deepest center, although the controlling depth is the outer channel in the port approaches with a dredged depth of . It serves as the harbo ...

, which is a deep channel between Mombasa island and South Coast mainland, is a ria.

Asia

Sanriku Coast The is a coastal region on the Pacific Ocean, extending from southern Aomori Prefecture, through Iwate Prefecture and northern Miyagi Prefecture in northeastern Honshū, which is Japan's main island. The name comes from the historical region of S ...

: North Japan, east coast of Honshū Island (main island). Sendai city, Miyagi Prefecture and Iwate Prefecture are included. * Ago Coast in

Shima Shima may refer to: Places , Japan * Shima Province (志摩), one of the old provinces of Japan * Shima, Fukuoka (志摩), a former town in Fukuoka Prefecture * Shima, Mie (志摩), a city in Mie Prefecture ** Shima, Mie (town), a former town ...

(Mie Prefecture) is a Ria coast, well known for its pearls. * Coasts on western, southern sides of the

Korean Peninsula Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...

: Rias formed by sea level rising after

Ice Age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

. * The Chinese east coast, from the

Guangdong province Guangdong (, ), alternatively romanized as Canton or Kwangtung, is a coastal province in South China on the north shore of the South China Sea. The capital of the province is Guangzhou. With a population of 126.01 million (as of 2020) ...

(

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China ( abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delt ...

coastlines included) to

Shanghai Shanghai (; , , Standard Mandarin pronunciation: ) is one of the four direct-administered municipalities of the People's Republic of China (PRC). The city is located on the southern estuary of the Yangtze River, with the Huangpu River flow ...

. * The

Musandam Peninsula The Musandam Peninsula ( ar, جَزِيْرَة مُسَنْدَم \ رَأْس مُسَنْدَم, Jazīrat Musandam / Raʾs Musandam), locally known as Ruus Al Jibal ( ar, رُؤُوْس ٱلْجِبَال, ''Ruʾūs al-Jibāl'' Heads of the Mou ...

Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of t ...

, comprising the southern shore of the

Strait of Hormuz The Strait of Hormuz ( fa, تنگه هرمز ''Tangeh-ye Hormoz'' ar, مَضيق هُرمُز ''Maḍīq Hurmuz'') is a strait between the Persian Gulf and the Gulf of Oman. It provides the only sea passage from the Persian Gulf to the ...

Oceania

* Papua New Guinea: Rias formed by eroded volcanic lava flow are found all around the town of

Tufi Tufi is a town located on the south eastern peninsula of Cape Nelson, Oro Province, Papua New Guinea. Tufi is located on one of many rias, or drowned river valleys, locally referred to as 'fjords', on Cape Nelson surrounded by many uncharted ree ...

at Cape Nelson, in Papua New Guinea's

Oro Province Oro Province, formerly (and officially still) Northern Province, is a coastal province of Papua New Guinea. The provincial capital is Popondetta. The province covers 22,800 km2, and has 176,206 inhabitants (2011 census). The province shares la ...

. * Australia: The east coast of Australia features several rias around

Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...

, including

Georges River The Georges River, also known as Tucoerah River, is an intermediate tide-dominated drowned valley estuary, located to the south and west of Sydney, New South Wales, Australia. The river travels for approximately in a north and then easterly ...

Port Hacking Port Hacking Estuary ( Aboriginal Tharawal language: ''Deeban''), an open youthful tide dominated, drowned valley estuary, is located in southern Sydney, New South Wales, Australia approximately south of Sydney central business district. Port ...

, and

Port Jackson Port Jackson, consisting of the waters of Sydney Harbour, Middle Harbour, North Harbour and the Lane Cove and Parramatta Rivers, is the ria or natural harbour of Sydney, New South Wales, Australia. The harbour is an inlet of the Tasman Sea (p ...

, which includes Sydney Harbour. There are many examples in

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

, including the Swan River around Perth and several rivers in the west Kimberley region. * New Zealand: Rias of various scales abound on the eastern shores of the upper

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 ...

. On the west coast, in contrast, they are fewer but larger.

Kaipara Harbour Kaipara Harbour is a large enclosed harbour estuary complex on the north western side of the North Island of New Zealand. The northern part of the harbour is administered by the Kaipara District and the southern part is administered by the Auckl ...

is the country's largest, and the

Hokianga Harbour The Hokianga is an area surrounding the Hokianga Harbour, also known as the Hokianga River, a long estuarine drowned valley on the west coast in the north of the North Island of New Zealand. The original name, still used by local Māori, is ...

, further north, is of historical significance to the native

Māori people The Māori (, ) are the indigenous Polynesian people of mainland New Zealand (). Māori originated with settlers from East Polynesia, who arrived in New Zealand in several waves of canoe voyages between roughly 1320 and 1350. Over several ce ...

. The

Marlborough Sounds The Marlborough Sounds are an extensive network of sea-drowned valleys at the northern end of the South Island of New Zealand. The Marlborough Sounds were created by a combination of land subsidence and rising sea levels. According to Māori m ...

at the northern tip of the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

form a large network of rias. *

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

Pearl Harbor Pearl Harbor is an American lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. It was often visited by the Naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U.S. with the signing of the Re ...

Oahu Oahu () (Hawaiian language, Hawaiian: ''Oʻahu'' ()), also known as "The Gathering place#Island of Oʻahu as The Gathering Place, Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over t ...

is a ria, with the branches of West Loch, Middle Loch, East Loch, and Southeast Loch formed by the submerged drainages of Waikele, Waiau, Waimalu, and Hālawa streams respectively.

North America

* United States:

Narragansett Bay Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound covering , of which is in Rhode Island. The bay forms New England's largest estuary, which functions as an expansive natural harbor and includes a small archipelago. Sma ...

New York Harbor New York Harbor is at the mouth of the Hudson River where it empties into New York Bay near the East River tidal estuary, and then into the Atlantic Ocean on the east coast of the United States. It is one of the largest natural harbors in t ...

Delaware Bay Delaware Bay is the estuary outlet of the Delaware River on the northeast seaboard of the United States. It is approximately in area, the bay's freshwater mixes for many miles with the saltwater of the Atlantic Ocean. The bay is bordered inlan ...

Indian River Bay Indian River Bay is a body of water in Sussex County, Delaware. It is part of Delaware's inland bay system, along with Little Assawoman Bay and Rehoboth Bay. Fed by the Indian River at its western end, the bay is connected to the Atlantic Ocea ...

, the

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the ...

, and

Charleston Harbor The Charleston Harbor is an inlet (8 sq mi/20.7 km²) of the Atlantic Ocean at Charleston, South Carolina. The inlet is formed by the junction of Ashley and Cooper rivers at . Morris and Sullivan's Islands shelter the entrance. Charleston H ...

are rias on the

East Coast East Coast may refer to: Entertainment * East Coast hip hop, a subgenre of hip hop * East Coast (ASAP Ferg song), "East Coast" (ASAP Ferg song), 2017 * East Coast (Saves the Day song), "East Coast" (Saves the Day song), 2004 * East Coast FM, a ra ...

Willapa Bay Willapa Bay () is a bay located on the southwest Pacific coast of Washington state in the United States. The Long Beach Peninsula separates Willapa Bay from the greater expanse of the Pacific Ocean. With over of surface area Willapa Bay is the ...

and

Grays Harbor Grays Harbor is an estuary, estuarine bay located north of the mouth of the Columbia River, on the southwest Pacific coast of Washington (U.S. state), Washington state, in the United States of America. It is a ria, which formed at the end of the l ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

and

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from a ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

on the

West Coast West Coast or west coast may refer to: Geography Australia * Western Australia *Regions of South Australia#Weather forecasting, West Coast of South Australia * West Coast, Tasmania **West Coast Range, mountain range in the region Canada * Britis ...

are also rias. * Canada:

Charlottetown Charlottetown is the capital and largest city of the Canadian province of Prince Edward Island, and the county seat of Queens County. Named after Queen Charlotte, Charlottetown was an unincorporated town until it was incorporated as a city in ...

Harbour,

Prince Edward Island Prince Edward Island (PEI; ) is one of the thirteen Provinces and territories of Canada, provinces and territories of Canada. It is the smallest province in terms of land area and population, but the most densely populated. The island has seve ...

South America

* Argentina:

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

has the Deseado ria, on the coast of Santa Cruz Province, on the

Atlantic Ocean 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 ...

. Also, the "bay" that is

Bahía Blanca Bahía Blanca (; English: White Bay) is a city in the southwest of the provinces of Argentina, province of Buenos Aires Province, Buenos Aires, Argentina, by the Atlantic Ocean, and is the seat of government of the Bahía Blanca Partido. It had 3 ...

is a ría.

Consequences

The funnel-like shape of rias can amplify the effects of

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

s, as demonstrated in the

seismicity of the Sanriku coast The seismicity of the Sanriku coast identifies and describes the seismic activity of an area of Japan. Seismicity refers to the frequency, type and size of earthquakes experienced over a period of time. The is a descriptive term referring to th ...

, most recently in the

2011 Tōhoku earthquake and tsunami The occurred at 14:46 JST (05:46 UTC) on 11 March. The magnitude 9.0–9.1 (M) undersea megathrust earthquake had an epicenter in the Pacific Ocean, east of the Oshika Peninsula of the Tōhoku region, and lasted approximately six minutes ...

Definitions

Locations

Europe

Africa

Asia

Oceania

North America

South America

Consequences

See also

References

Further reading