The Congo River (also known as the Zaire River; ; ) is a river in Africa. It is the second largest river in the world by discharge (after the Amazon), and the world's deepest river with measured depths in excess of . The Congo-Chambeshi river has an overall length of , which makes it the ninth  longest river (in terms of discharge, the Chambeshi is a tributary of the Lualaba River, Lualaba being the name of the Congo River upstream of the Boyoma Falls, extending for 1,800 km). Measured along the Lualaba, the Congo River has a total length of . It crosses the equator twice. The Congo Basin has a total area of about 4 million km², or 13% of the entire African landmass.