The San Matias Gulf is an inlet of 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 ...

off the coast of

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 g ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...

. It is bordered by the

Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its capi ...

to the north and west, and the Valdes Peninsula of the

Chubut Province Chubut ( es, Provincia del Chubut, ; cy, Talaith Chubut) is a province in southern Argentina, situated between the 42nd parallel south (the border with Río Negro Province), the 46th parallel south (bordering Santa Cruz Province), the Ande ...

to the south. It is "one of the largest gulfs in the Patagonia region". The gulf is surrounded by plateaus and depressions below sea level similar to the gulf itself but that are not flooded by the sea at present. The gulf was the subject of scientific investigation for its unusually large sand waves and their movement. The local fishing industry may be unsustainably harvesting the purple clam ('' Amiantis purpurata''), the Tehuelche scallop (''

Aequipecten tehuelchus ''Aequipecten tehuelchus'' is a species of bivalves belonging to the family Pectinidae Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the co ...

''), the

blue mussel The blue mussel (''Mytilus edulis''), also known as the common mussel, is a medium-sized edible marine bivalve mollusc in the family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. A species with a l ...

(''

Mytilus edulis The blue mussel (''Mytilus edulis''), also known as the common mussel, is a medium-sized edible marine bivalve mollusc in the family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. A species with a l ...

''), and the ribbed mussel ('' Aulacomya atra''), as well as the Patagonian octopus ('' Octopus tehuelchus''). The 2003 commercial

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fittin ...

harvest broke the previous record set in 2001 by more than double at . As of 2014, this gulf is the only location in the world where swimming with whales is permitted for tourism, with

right whale Right whales are three species of large baleen whales of the genus ''Eubalaena'': the North Atlantic right whale (''E. glacialis''), the North Pacific right whale (''E. japonica'') and the Southern right whale (''E. australis''). They are c ...

s. The San Matías Gulf has a history of tectonic origin. Prior to the

deglaciation Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to the retreat of a glacier, an ice shee ...

that followed the last glacial period San Matías Gulf was a dry flatland below

sea level 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 standardis ...

. As global deglaciation went on after the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eu ...

sea level rose so that 11,000 years before present sea level surpassed the San Matías sill flooding the whole basin. This sill is currently 60 meters below sea level. The gulf has been repeatedly dried up and flooded during

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...

and

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...

periods respectively.

References

Gulfs of the Atlantic Ocean Bays of Argentina {{marine-geo-stub