river in eastern New Guinea, Papua New Guinea, southwestern Pacific Ocean. Rising on the southern slopes of the Bismarck Range of the central highlands, it flows southwest and south for some 290 miles (470 km) to the Gulf of Papua of the Coral Sea. In the highlands the Purari, fed by its principal headstreams, the Erave, Kaugel, and Tua rivers, flows through gorges and densely populated areas, including the towns of Gurimatu and Wabo. Its middle course crosses a forested coastal plain. In its lowest 25 miles (40 km) the stream subdivides into five main channels, which lace through a well-settled 1,000-square-mile (2,600-square-km) swampy delta. The river empties into the Orokolo Bay of the Gulf of Papua and drains an area of some 12,750 square miles (33,000 square km). It is navigable for approximately 120 miles (190 km) above the mouths. Although partially charted by the British explorer Theodore Bevan in 1887, the river system was not fully traced until the 1930s. The river's suitability for a major hydroelectric dam was studied during the 1970s and again in the early 21st century, but no plans are yet in place to undertake such a project.