At present, the Mamberamo remains the second largest river in the world to be completely unfragmented by dams in its catchment, behind only the relatively nearby Fly.

The region is geologically young (middle to late Miocene, i.e. less than 15 million years old) and remains tectonically active, with frequent earthquakes and landslides in the steepest areas.

The mountain basin called "Mamberamo" is composed mostly of high floodplains, extensive swamps, forested wetlands, meandering rivers and backwater lakes.

Riparian forests within the Mamberamo Basin are heavily influenced by dynamic river meanders that continually modify the landscape, with some banks eroding rapidly while others grow as new sediments accumulate.

Mixed crop gardens are located near the dwelling or on the river banks and are mostly planted with sweet potatoes (Ipomoea batatas) and manioc (Manihot utilissima).

The globally endangered Scott's kangaroo (Dendrolagus scottae) is thought to occur in the Foja Mountains, while the northern cassowary (Casuarius unappendiculatus), Victoria-crowned dove (Goura victoria) and black-spotted couscous (Spilocuscus rufoniger) form significant populations.

As well as several new species, including the honeyeater (Melipotes carolae), the pigeon (Duculas), the dwarf opossum (Cercartetus), the giant rat (Mallomys), a Dorcopsulus and a bow-fingered gecko (Cyrtodactylus).

[11] In 1545, the Spanish navigator Iñigo Ortiz de Retes sailed along the northern coast of the island as far as the mouth of this river that he charted as San Agustín.

At this spot, on 20 June 1545, he claimed the territory for the Spanish Crown, and in the process bestowed the name to the island (Nueva Guinea) by which it is known today.

[12] The following year in 1884 Van Braam Morris returned to the steamship Havik and travelled 60 mi (97 km) (as the crow flies) along its course.