Paraguay River, << PAR uh `gway` or PAR uh `gwy,` >> is a waterway that flows south through Paraguay, cutting the country in two. It is a branch of the Parana River and rises in south-central Brazil. From there, it flows south and joins the Parana at the Argentine boundary. The Paraguay is 1,584 miles (2,549 kilometers) long. The Paraguay is a good river for navigation, except for channel shifts. Large steamboats go up the Parana and continue on the Paraguay to Asuncion, the capital of Paraguay. See also Parana River .