The falls are the lowest of a long series of rapids that render the river unnavigable, forcing colonial explorers to travel by foot as far as the Stanley Pool 350 kilometres (220 mi) upstream.

[3] The region drained by the Congo River covers one eighth of Africa, including both tropical rain forest and savanna, much of it in a huge, shallow basin.

A large lake formed before the Congo River broke through this barrier, running through a narrow, rocky channel about 350 kilometres (220 mi) long from Kinshasa to Matadi.

[4] The upper portion of the Lower Congo starts with the steep Livingstone Falls just below Kinshasa and continues for 133 kilometres (83 mi) through a number of smaller rapids.

[10][fn 1] In 1848 the Hungarian László Magyar ascended the Congo to the Yellala falls, before spending five years exploring the region to the south.

Afterwards, the water heads down a slope of around thirty feet "in 300 yards, spuming, colliding and throwing up foam, which looks dingy white against the dull yellow-brown of the less disturbed channel - the movement is that of waves dashing upon a pier".

[13] He went on: "The old river-valley, shown by the scarp of the rocks, must have presented gigantic features, and the height of the trough-walls, at least a thousand feet, gives the Yellala a certain beauty and grandeur.

[14] The explorer Henry Morton Stanley, who visited the falls on April 6, 1880, wrote that over a five or six mile stretch the incline was only 45 feet (14 m), but that the "general fury of the water is caused by the obstructions which the giant volume meets in the bed of the narrow defile.