San Antonio Oeste is a port town in eastern Río Negro, at the head of the San Matías gulf. It's the urban and service center of the area, the seat of the San Antonio department, and the administrative and transport base for the tourist region that includes the famous Las Grutas beach resort, about 15 km away, and the fishing village of San Antonio Este.
Its great natural asset is the Bahía de San Antonio Protected Natural Area, a coastal wetland of international importance for migratory shorebirds. Every year thousands of birds — among them the red knot, which travels from the Arctic to Tierra del Fuego — stop over on its salt marshes and rock shelves, making the bay a key site in the Western Hemisphere Shorebird Reserve Network.
For travelers, San Antonio Oeste works in two ways: as a quieter, cheaper base for the mild waters of Las Grutas — connected by an intercity bus every few hours — and as a nature destination in its own right, with birdwatching in the bay, sport fishing in the San Matías gulf, the fishing village of San Antonio Este with the untouched beaches of Punta Villarino, and, inland, the lunar landscape of the Salinas del Gualicho. Getting there is easy: there are direct coaches from Buenos Aires, Bariloche and Viedma, and the Tren Patagónico stops in town.
San Antonio Oeste was officially founded on 10 July 1905, when a ship belonging to the firm Sassenberg & Cía reached the Caleta del Oeste to set up a port at the head of the San Matías gulf. In 1908 work began on the railway towards Nahuel Huapi, directed by the engineer Guido Jacobacci, and on 5 May 1934 the first locomotive reached Bariloche. In the 1930s the port became the country's second-largest wool market. Historically tied to the port, fishing and transport, today it's the service center of a tourist region dominated by the Las Grutas resort and birdwatching in the bay.
Read the full history ↓The province that crosses Patagonia from the cordillera to the sea: Tehuelche and Mapuche land, land of Carmen de Patagones and the Conquest of the Desert, of the apples of the Alto Valle, of Bariloche and the Nahuel Huapi, and of the beaches of Las Grutas.
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Origins, formation and what the sources say.
There is one detail about the San Matías gulf that surprises anyone arriving for the first time: in neighboring Las Grutas the sea can be as mild as in the Caribbean, something almost unheard of on the Patagonian coast. The secret lies in the tidal range, one of the largest in Argentina, which exposes and warms enormous rock shelves that the water then washes over. That natural phenomenon, today the basis of the region's beach tourism, is just one layer of a much longer story that begins thousands of years before any town existed. Long before the town was founded, the shores of the San Matías gulf were inhabited by hunter-gatherer indigenous peoples who lived off the resources of the sea and the steppe. The shell middens and archaeological remains found in the area point to a human occupation going back millennia, tied to gathering shellfish, fishing and hunting sea lions along the coast.
The San Matías gulf was sighted by European navigators from the 16th century onwards: its name is attributed to the expedition that followed the Patagonian coast in the era of the first exploratory voyages of the South Atlantic. For centuries, though, the region remained on the margins of colonial rule, crossed by Tehuelche peoples and, later, by groups tied to trade and to the indigenous routes of Patagonia.
The gulf's great tidal range — one of the largest in the country — and the abundance of marine wildlife would later prove key both to the fishing economy and to the ecological value that today sets the bay apart. That natural framework shapes the whole later history of the settlement.
The founding date of San Antonio Oeste is 10 July 1905, the day a ship belonging to the firm Sassenberg & Cía reached the Caleta del Oeste to set up at the head of the San Matías gulf. An earlier settlement already existed at the spot known as Saco Viejo, but the lack of drinking water pushed the population towards the western side of the cove, where the definitive town was born. This was a time when the Patagonian coast was being fully incorporated into the Argentine state, and with no roads, the port became vital: through it went wool, hides and feathers from the estancias of inland Río Negro on their way to Buenos Aires.
The big boost came with the railway. In 1908 the construction of the line towards Lake Nahuel Huapi was announced and the first engineers arrived, headed by Guido Jacobacci, along with hundreds of laborers who began laying track from the port of San Antonio towards the Andes. The work crossed the steppe over decades until, on 5 May 1934, the people of Bariloche watched the first locomotive arrive: the Atlantic coast and the Andean region were finally joined by rail, with San Antonio Oeste as the eastern terminus.
Its port and railway role defined the town's life for decades: in the 1930s its natural harbor became the country's second-largest wool market. Although that activity declined once the train linked Buenos Aires directly with Bariloche and San Antonio became a through station, that logistical root explains why the town established itself as the urban and service center of the whole area, a role it keeps today as the main town of the gulf's tourist region.
Over the 20th century, San Antonio Oeste gradually broadened its profile. While the port and fishing remained important — with the later development of the deep-water port at San Antonio Este — the great transformative phenomenon was the rise of tourism in nearby Las Grutas, whose mild-water beaches drew a growing number of holidaymakers from the middle of the century onwards. The town became the logistical and service support for that tourist hub.
At the same time, the region's extraordinary natural value came to the fore. The Bahía de San Antonio turned out to be a wetland of international importance for migratory shorebirds, which use it as a resting and feeding site on their journeys across the Americas. Its inclusion in the Western Hemisphere Shorebird Reserve Network (WHSRN), in the 1990s, put the area on the map of continental-scale conservation, and in 1993 the Bahía de San Antonio Protected Natural Area was created.
So the old port town today combines several identities: its roots in port work and fishing, its role as the service center of a fast-growing beach destination, and its value as a key point for birdwatching and for conservation on the Patagonian coast. That mix of history, economy and nature defines the character of San Antonio Oeste.
Today San Antonio Oeste is the seat of a department made up of three complementary centers: the town itself, as the administrative and service hub; Las Grutas, the resort that concentrates summer tourism; and San Antonio Este, with its deep-water port and its more solitary beaches. That three-part structure is unusual and defines the identity of the San Matías gulf micro-region.
The local economy rests on seasonal tourism, fishing, port activity and services. In summer the population multiplies with holidaymakers arriving in Las Grutas, drawn by the unusually warm sea temperature, a product of the enormous tidal range that warms the water over the broad rock shelves. Out of season, the town recovers the quiet rhythm of a Patagonian coastal town.
San Antonio Oeste's contemporary challenge is to reconcile tourism growth with conserving the bay's wetland, a natural asset of global value. Bird festivals, censuses, environmental education and nature tourism coexist with sun-and-beach tourism, in a region trying to balance development with protection of the coastal environment.
To understand San Antonio Oeste and its surroundings you first have to understand its tides, because almost everything else — the port, the fishing, the Las Grutas resort and even the bay's richness for birds — is explained by that phenomenon. The San Matías gulf has one of the largest tidal ranges in Argentina: the difference between low and high tide can exceed several meters, exposing, twice a day, kilometers of rock shelves, mudflats and sandbanks that are completely submerged at high tide.
That extreme dynamic has very concrete consequences. In Las Grutas, the sun heats those broad stone shelves for hours when the sea withdraws, and when the tide comes back in, the water advancing over that hot rock warms up noticeably, producing sea temperatures unusually high for the Patagonian latitude. That is, to a large extent, why thousands of holidaymakers choose this coast in January and February over colder Atlantic beaches.
In the Bahía de San Antonio, the same mechanism of extreme tides creates a unique habitat: salt marshes and tidal flats extremely rich in small invertebrates — worms, molluscs and crustaceans — that are only within reach of the shorebirds during the hours of low tide. That's why local guides don't schedule watching trips at a fixed time but according to the tide table: each outing is organized around the moment the mud is exposed and the birds come down to feed. The tidal range, then, isn't just another curious fact: it's the physical key that connects port life, beach tourism and wildlife conservation across the whole San Matías gulf region.
