[5] 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.

As part of this deal, Indonesia has the right to use the Fly River to its mouth for navigation.

The distributary channels are 5 to 15 m in depth, separated by elongate, sand-mud islands that are stabilized by lush mangrove vegetation.

Upstream from the apex the river gradually narrows to a width of 1.6 km or less.

The islands in the estuary are flat and covered with thick, fertile alluvial soil.

[21] In 1876, Italian explorer, Luigi D'Albertis, was the first person to successfully attempt this when he travelled 900 km into the interior of New Guinea, in his steamer, Neva.

Sediment sampling and coring in the distributary channels of the Fly Delta had not detected copper concentrations significantly higher than background as of 1994.

[22] In 2008, Ian Campbell, a former advisor to Ok Tedi Mining Limited, claimed that company data suggest significant portions of the Fly River floodplain are at a high risk from acid mine drainage.