Río Santa Lucía flows through the subtropical lowlands of Corrientes Province, Argentina, eventually emptying into the mighty Río Paraná. The river drains a vast watershed characterized by the region's signature low-gradient terrain, giving rise to extensive wetland systems including the Estero Santa Lucía — a sprawling complex of marshes, shallow lagoons, and seasonally flooded grasslands that defines much of the river's character. The surrounding landscape is a mosaic of quebrachal woodlands, palm savannas, pajonales (tall grass marshes), and gallery forests, all of which contribute to the river's rich aquatic ecosystem. The waters of the Santa Lucía are notably transparent, offering anglers excellent visibility into the river's structure and allowing for sight-fishing opportunities in certain stretches. The river's principal tributaries include the San Pedro, Artaza, and Carballo streams, each adding flow and forage to the main channel.