Flowing through the remote wilderness of the Gran Chaco in northern Argentina, the Río Bermejo is one of South America's most dramatic and untamed fishing destinations. Rising near Tarija, Bolivia, in the Sierra de Santa Victoria, the river plunges down to the Chaco lowlands before meandering some 1,046 kilometers southeastward, ultimately joining the Paraguay River opposite Pilar, Paraguay. The river forms the natural border between Formosa and Chaco provinces and carries an enormous sediment load — the source of its name, bermejo meaning "reddish color" in Spanish. This turbid, powerful waterway winds through dense thorn forest and the lands bordering the Impenetrable Chaco National Park, a landscape teeming with jaguars, giant armadillos, peccaries, and macaws. For anglers willing to venture into one of the continent's last true wilderness corridors, the Río Bermejo offers an extraordinary opportunity to pursue trophy-class freshwater predators in an environment that few outsiders ever experience.