Genre: Information/Explanation

The vast expanse of the African continent spans several different climatic regions and contains everything from dry deserts to rainforests to snow-covered mountaintops . Check out some of the most-impressive physical features found in Africa . Congo River Coursing through the heart of Africa , the Congo is the continent's second longest river , after the Nile . It is contained primarily in , or marks the border of , the Democratic Republic of the Congo . The river is approximately 2,900 miles ( 4 , 700 km ) long and , with its many tributaries , forms the largest network of navigable waterways in Africa ; this is in spite of the difficulty in navigating the lower course of the river , which has 32 cataracts ( waterfalls ) . The Congo River is home to hundreds of species of fish , many of which are endemic to the river . There are few aquatic mammals in the river , but various types of reptiles , such as crocodiles , semiaquatic tortoises , and water snakes , reside there . Georg Gerster / Comstock Inc. The Sahara The Sahara , which takes its name from the Arabic word for " desert , " is the largest hot desert in the world . With a total approximate area of 3.32 million square miles ( 8 . 6 million square km ) , it encompasses almost all of northern Africa , spanning from the Atlantic Ocean on the western side of the continent to the Red Sea on the eastern side . About one-fourth of the Sahara's surface consists of sand sheets and dunes ; other principal features include sand seas , gravel-covered plains , rocky plateaus , abrupt mountains , shallow basins , and large oases . In general , vegetation in the Sahara is limited to areas around oases , wadis ( riverbeds that are usually dry outside the rainy season ) , and the highlands . The desert has a perhaps-surprising amount of wildlife , including hundreds of types of birds ( including resident as well as migratory birds ) , gerbils , jackals , mongooses , frogs , lizards , cobras , and snails that can remain dormant for several years until they are revived by rainfall .