The Río Paraná is one of South America's most iconic and powerful river systems, draining a massive watershed of approximately 2,400,000 km² across Brazil, Bolivia, Paraguay, and Argentina. Originating in Brazil, the river flows southward through Paraguay and into Argentina before emptying into the Río de la Plata. In Argentina, the Paraná forms the natural boundary between several provinces, with the middle and lower reaches running through the province of Santa Fe for more than 800 km. This stretch of river is defined by a vast, dynamic floodplain with an intricate anabranching network of channels, fluvial lakes, swamps, vegetated islands, and residual floodplain channels. Secondary channels are typically around 50 meters wide but are deeply cut and fast-flowing, maintaining permanent hydraulic connections with the main river and its floodplain. The result is a complex, ever-shifting mosaic of habitats that supports extraordinary biodiversity — and some of the most exciting freshwater fishing in the world.