The estuary has been designated as a Ramsar site since 1992. The 30,000 ha site mainly consists of mangrove forest and intertidal mudflat habitats. African manatees are present. The site has also been designated an Important Bird Area by BirdLife International because it supports significant populations of waterbirds.
Part of the plot of the historical novelAnthony Adverse – and the film made on it – is chiefly set on the Pongo River, in the last years of the 18th century and the first years of the 19th. The book's eponymous protagonist – an adventurous and highly capable young man – arrives from Cuba and in a brief time takes personal control of slave trading along the river. He amasses a considerable personal fortune, but at the price of becoming increasingly corrupted. Finally being sickened by slaving, he departs for other adventures in other continents.