Geography & Climate
The Sepik River is 1126km long and is navigable for almost its entire length. It starts up in the central mountains, close to the source of PNG’s other major river, the Fly, which flows south. The Sepik flows in a loop, first west across the West Papua border, then north before returning east across the border.
At its exit from West Papua, the Sepik is only 85m above sea level and from there it gradually winds down to the sea – a huge, brown, coiling serpent. It has often changed its course, leaving dead-ends, lagoons, oxbow lakes or huge swampy expanses that turn into lakes or dry up to become grasslands in the dry season.
The inexorable force of the river tears great chunks of mud and vegetation out of the riverbanks and these drift downstream as floating islands. There is no delta and the river stains the sea brown for 50km or more from the shore.
Early in the dry season is the best time to visit – natnats (mosquitoes) are less numerous and there’s plenty of water in the river system. By August the level drops significantly emptying some tributaries and barets (artificial channels cut as shortcuts across loops in the river), and this makes travel times much longer and the river unnavigable in parts.