The Fly at , is the second longest river in Papua New Guinea, after the Sepik. The Fly is the largest river in Oceania, the largest in the world without a single dam in its catchment, and overall ranks as the 25th-largest river in the world by volume of discharge. It rises in the Victor Emanuel Range arm of the Star Mountains, and crosses the south-western lowlands before flowing into the Gulf of Papua in a large delta.