Misiones Aguas Abiertas

The Paraná River at Posadas carries the weight of a geologic shift that occurred ten millennia ago, when its currents finally carved through a stubborn basaltic massif that had previously forced the waters toward Brazil. This breakthrough created the dramatic 90-degree bend defining the local landscape, a sharp turn that swimmers navigate during the 10km traverse between Balneario Costa Sur and Balneario El Brete. Beneath the surface, the riverbed tells the story of the Yacyretá Dam, which in 2008 raised water levels by seven meters, permanently altering the shoreline and submerging the historic San José lagoon. Today, the water remains a powerful, moving presence, characterized by a mix of muddy natural banks and engineered sandy stretches designed for public access.

Race day logistics

Participants in this annual February event, organized by the Club Náutico León Seró, face a point-to-point course that demands consistent pacing against the river's flow. While the scenery includes views of the 2,550-meter cable-stayed bridge connecting Argentina to Paraguay, the swimming experience is anchored in the region’s defensive heritage; the route runs roughly parallel to where the 19th-century Trinchera de los Paraguayos once used ancient stone structures to guard the territory. Logistics are managed through a comprehensive safety protocol, providing each swimmer with a personalized buoy, a hydration kit, and constant escort by kayak and motorboat support. The high level of technical oversight and water-based coordination justifies the registration structure, ensuring that the 10km challenge remains organized and monitored throughout the crossing.

Historical currents

History here is never far from the water. The reduction of Nuestra Señora de la Anunciación de Itapúa, established on these banks in 1615 by Roque González de Santa Cruz, serves as a reminder of the Jesuit presence that shaped the early settlement before it moved across the river. As you stroke through these currents, you pass the same geography that dictated the movements of regional forces during the construction of the defensive wall between 1838 and 1840. The current race serves as a contemporary marker for a city that has spent centuries defined by its relationship with the Paraná.