From recent study, scientists have come to believe that the Sahara Desert grows and shrinks on a regular basis. It receives less than three inches of rain a year. In the wettest areas even, it may only rain once or twice a week and not rain again until a couple years. The Sahara Desert is the world's largest desert . It takes over about a third of the African continent, about the size of the United States. The Sahara Desert is also one of the hottest places on Earth, temperatures may rise to 136 degrees F. That's 57.7 degrees C. It is between 800 and 1200 miles, and is at least 3000 miles from east to west. Sahara is bordered by the Atlantic Ocean, Mediterranean Sea, and the Red Sea, and just north is the Atlantis Mountains. Had intense human hunting for that past 100 years. It is a vast area of largely undisturbed habitat, principally sand and rock, but with small areas of permanent vegetation. The Sahara Desert isn't a very protected area either. They are not highly threatened by human activities. The only local pressure where the resources can be intense is areas of permanent water or in areas where water comes close to the surface. The populations of all species have been reduced a lot from hunting for food and through hunting for sport and recreation. The Sahara Desert is part of several African nations including Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan and Tunisia. The Sahara Desert has been shaped over time by wind. About 25% of the desert is just sand dunes. There are several mountain ranges in the desert, and many of them are volcanic. It has experienced many climate changes in the past 100 years. This desert only has 2 permanent rivers, and a handful of lakes. It has a good amount of aquifers in the desert though. The permanent rivers are the Niger River and the Nile River. It has 20 or more lakes but only 1 with potable water.