Summer Open Water — Viedma · Patagones

The Summer Open Water — Viedma · Patagones is an open water swimming event held directly in the fresh waters of the Río Negro, right in the Comarca Viedma-Patagones where the river divides the province of Río Negro from Buenos Aires. For the twin communities established on opposing riverbanks, this massive waterway is not merely a geographic landmark, but a central pillar of local culture and identity. Held over a summer weekend in January, the Summer Open Water — Viedma · Patagones spreads its racing schedule across multiple competitive distances on the Río Negro, offering 2,000, 5,000, and 10,000-meter courses. The program features an evening 2K Nocturno alongside the daytime 5,000 and 10,000-meter marathon swims.

Taking on the Río Negro presents swimmers with living, moving water, where natural river currents and shifting surface conditions demand steady pacing and good sighting between buoys. Far from the biting cold often associated with Patagonia, the summer river reaches comfortably mild temperatures that make the swim exceptionally pleasant and well-suited for skins swimming without a wetsuit. In past seasons, the event has featured a buoyed circuit where competitors circled 2.5-kilometer river loops while enthusiastic spectators crowded along the shoreline banks to cheer them through each turn. Once out of the river, competitors and companions convene at the Parador Náutico of Club Náutico Piedra Buena for the post-race gathering. There, swimmers trade stories of the current and celebrate the day's crossings.

Río Negro and Laguna El Juncal: river hydrology and fauna

The Negro River ranks as the largest river in Argentine Patagonia and stands among the five most voluminous watercourses in the entire country. Its broad expanse and constant volume also serve an environmental role for the valley, helping to temper and moderate the local climate. Life along the water remains remarkably diverse, especially around the tranquil islets that dot the river course near the cities. Around spots such as Isla Lucas Perez, native waterbirds include black-necked swans, river ducks, and coots navigating the quiet reeds. In the winter months, marine dolphins known locally as toninas travel inland directly from the open ocean, swimming upstream along the lower channel of the Río Negro.

Roughly eleven kilometres from the modern race zone sits the dry expanse of Laguna El Juncal, an immense natural wetland that once ran parallel to the river for sixty kilometres in length and four kilometres in width. The river valley's immense water volume repeatedly broke its bounds over the nineteenth century, unleashing severe floods in 1829, 1870, and 1899. The catastrophic inundation of July 1899 destroyed Viedma and dismantled the chain of military fortifications along the watercourse, forcing officials to evacuate the seat of government entirely. To halt these destructive overflows and open productive ground for livestock grazing, engineers undertook extensive drainage works that had completely dried the historic lagoon by the 1930s.

Carmen de Patagones: naval battles and buried wrecks

The strategic command of the river prompted early colonial expansion, starting when Francisco de Viedma founded the Fort of Nuestra Señora del Carmen alongside the town of Nueva Murcia on the southern bank in 1779. Nearly a century later, on October 11, 1878, the Río Negro officially became the recognized administrative boundary dividing Buenos Aires province from the Patagonia Governorate. As maritime trade developed, the isolated riverside settlement held key commercial importance. On July 21, 1810, the governing Junta granted Patagones exclusive authority over the lucrative salt supply shipped to the city of Buenos Aires. Controlling this southern river entrance led to several tense naval encounters during early conflicts. In May 1812, the revolutionary brig Hiena was anchored in San Blas bay when royalist rebels staged a beach ambush on its crew under the cover of cutting piquillín bushes for firewood before seizing the ship.

Another vessel, the merchant brig Amazona, was captured by rebel forces in the roadstead of Carmen de Patagones, but was wrecked upon the coast while attempting to exit the Río Negro. A maritime encounter took place in 1827 during the Batalla de Carmen de Patagones, situated about three kilometres from the swim area. A Brazilian naval squadron entered the river, but the deep-draft corvette Duqueza de Goyas ran firmly aground in the river channel.

The Comarca riverfront: twin cities and estuary beaches

Today, the riverfront forms the shared heart of the Comarca, where Viedma occupies the southern bank and Carmen de Patagones faces it across the current on the northern shore. The Río Negro marks the dividing line between these two twin cities, which are connected above the water by a bridge. The Proyecto de distrito federal Viedma-Carmen de Patagones envisioned building a brand-new federal capital on the banks of the Negro River linking both towns. The region's growing profile also welcomed Pope John Paul II in April 1987, who became the only Roman pontiff ever to set foot in Patagonia.

Following the river down toward the ocean reveals the dramatic transition from freshwater current to maritime surf. At the river mouth sits Balneario El Cóndor, originally known as Balneario La Boca. On the northern shore of the estuary, the coastal village of 7 de Marzo was established in 1993, looking out where the mighty river terminates in the Atlantic. Back upriver along the Comarca, the Summer Open Water offers swimmers the chance to experience this storied Patagonian river at its warmest and most vibrant.