The Kouilou-Niari River — also spelled Kwilu, Kwila, or Kwil — is the most important river flowing to the Atlantic ocean of the Republic of the Congo coast. Moreover, it entire drainage area is completely in the Republic of the Congo. The river is called the Kouilou River while flowing in the coastal region of the Kouilou till the Sounda gorges. Upstream from the Gorges, its name is the Niari and it flows through the Niari Valley. The river combines with the Louessé River, the Loudima and the Bouenza and eventually flows into the Atlantic Ocean.