The Amazon’s blackwater giant begins as Colombia’s Guainía
The Rio Negro—Guainía in its upper Colombian reach—is the Amazon’s largest left-bank tributary, delivering about fourteen percent of basin water. It is the world’s largest blackwater river and ranks among the ten biggest rivers by average discharge, rising in Guainía Department before meeting the Solimões at the Meeting of Waters.
From the Puinawai National Reserve the river trends east-north-east past Indigenous settlements, then swings south-east by San Carlos de Río Negro, the largest Venezuelan town on its banks, and Colombia’s San Felipe. For about 260 kilometres it marks the Colombia–Venezuela border until Piedra del Cocuy, a Precambrian outcrop of the Guiana Shield.
In the wet season, from around April, floods can spread the river roughly thirty kilometres wide over long distances. Anavilhanas National Park protects 350,018 hectares of river islands, first reserved as an ecological station in 1981. Below that archipelago the dark water runs alongside the muddy Solimões before the two blend into the Amazon proper.
Despite the name, the water is closer to strong tea than ink; humic acid from partly decomposed vegetation on sandy ground stains it, and from a distance it looks black. Blackwater rivers were once dismissed as hunger rivers, but newer research credits the Negro with a large fishery and many turtle nesting beaches. The sparse Indigenous population explorers met in the seventeenth century probably reflected disease and war more than any poverty of the river.
Francisco de Orellana came upon and named it in 1541. By the mid-1600s Jesuits had settled among the Manau, Aruák and Tarumá peoples, and after 1700 slaving was widespread. Humboldt and Bonpland explored it in 1800, and Richard Spruce and Alfred Russel Wallace collected plants and made observations there between 1852 and 1854. Alexander H. Rice of Harvard travelled up the Orinoco, through the Casiquiare and down the Negro to Manaus in 1924 and 1925, the first expedition to map the region with aerial photography and shortwave radio.
Source: Rio Negro (Amazon)
