The Congo River's Path

The sprawling Congo is the fifth-longest river in the world and the second-longest river in Africa (after the Nile). Its muddy waters run alternately slow and fast, shallow and deep. The river is a playground -- and mating ground -- for animals like the hippopotamus and crocodile. And it's the financial artery that makes trade possible; there's no way into the heart of the Congo except by the river. Much of the Congo is impassible except by pirogues -- dugout canoes. And only the truly adventurous ever traverse these parts of the river. Large trading vessels, such as steamboats, can travel about 9,000 miles (14,500 km) of the river en route to their ports from Kinshasa, Congo's capital, to the Atlantic Ocean.

The Congo River runs north and west, ending at the Atlantic. Its course flows north to Stanley (or Boyoma) Falls, a massive waterfall named after explorer Henry Stanley, and then veers west and then south, where it empties into the ocean. This massive river encompasses 10,000 streams and covers 2,900 miles (4,667 km). It takes six months for water to cycle from the river's source to its end [source: BBC]. The Congo snakes across the equator twice, and its broadest stretch is nearly 10 miles (16 km) across.

There are four sections of the river: headwaters, upper Congo, middle Congo and lower Congo. We'll begin at the headwaters, or the source of the river.

In southern Congo, the Lualaba and Lapula Rivers join and form the origins of the Congo River. The Lualaba is also known as nZaire -- "the river that swallows all rivers." The water here is very rough.

The upper Congo extends from the Lualaba River to the north. Here, the river flows toward Stanley/Boyoma Falls, where raging waters plummet 1,520 feet (460 m). Only 200 miles (300 km) of the upper Congo is fit for watercraft. Some cartographers consider upper Congo an extension of the Lualaba [source: MSN Encarta].

Per-Anders Pettersson/Getty Images
In April 2006, children play outside a hut in a fisherman camp along the Congo River, just outside of Bumba.

Past the falls, the middle Congo begins. This section of the river is 1,000 miles (1,600 km) long and is easily navigable. While the water runs still, the course is quite crooked. The river shifts northwest, then west and finally southwest. It also incorporates four of the Congo's largest tributaries (waters that feed a larger water body): the Aruwimi, Kasai, Lomami and Ubangi rivers. The river becomes very wide at a lake named Pool Malebo, near the island of Mbamou.

At the lower Congo, rough, rushing waters are created when the river tapers and gushes through narrow banks. This part of the river measures 270 miles (435 km). Its path surges from Pool Malebo to the Atlantic Ocean, where the river ends. Nearly 95 miles (153 km) from the Atlantic, the rapids subside at Port Matadi. This is the last trading point before the river's end. Where the Congo meets the Atlantic, it comes raging in at one million cubic feet per second -- a surge mighty enough to carve nearly one mile-deep rivulets in the ocean floor [source: Mealer].

Because the Congo flows through the rainforest, it's able to retain most of the water it absorbs from the dense, humid air -- between 75 and 95 percent [source: WWF].

But it's not just the sound of flowing water you'll hear along the river. Listen for bird calls, the splash of hippos and the steady rhythm of tribal drums. What -- and who -- lives along the Congo? We'll find out next.