The Uele–Mbomou confluence at Yakoma marks the origin of theUbangi River, which in turn flows into theCongo River. The Uele is the longest tributary of the Ubangi. The combined Ubangi–Uele length is about 2,270 kilometres (1,410 mi).[3]
From satellite images, parts of the river look red from theiron oxide contaminants in the river.[citation needed]