The Fly River is the next longest river in Papua New Guinea after the Sepik River. The 1,050 kilometres long river originates from the arm of the Victor Emanuel Range sited in the Star Mountains and flows to the south-west part of the lowlands and finally passes to the Gulf of Papua and spreads across a large delta. The Fly river mostly flow in the Western Province and acts as a boundary between the Indonesia province of Papua and the Papua, New Guinea. The major Fly tributaries are the Ok Tedi and the Strickland.
As the entry, the river estuary is 56 km wide and the subsequent Kiwai Island is 11 km wide and marked as the river mouth.
The river forms a number of delta islands that are usually low and swampy and covered in a thick and fertile alluvial soil. They are namely the Kiwai Island, the Magabu Island, the Purutu Island, the Mibu Island, the Sisiabu Island, the Aibinio Island, the Nikira Island, the Moroge Island, the Wabuda Island, the Badu Island, the Invitato Island and the Aeginimi and Umuda Island, the Kuragimini and Kunagimini Islands Island, the Domori and Dubuwaro Island, the Baiabe Island to name a few and most of them are covered with nipa palm and mangrove.
The residents of the Fly River delta practices hunting and agriculture. The most popular plants grown here are coconut and sago palm, breadfruit, sugar cane and plantain. But today the Fly tributaries of the Ok Tedi and Strickland rivers are running a high risk due to acid mine drainage as the tailings waste are continuously thrown from the surrounding mines of Porgera and the Ok Tedi Mine.