The Sahara Desert: Everything to Know About the Largest Desert in the World

It is the biggest desert of its kind in the world — almost as big as the entirety of the United States.

Despite its desolation, it is nevertheless home to millions of people and hundreds of species of plant and animal life. It is dry, hot, and inhospitable in a way that would be hard for many people on the planet to fathom, yet it is also a land of incredible life and diversity. Here’s what we know about the Sahara Desert.

Probably the first thing worth knowing is that the Sahara is not, in actuality, the biggest desert on the planet. At their most basic, deserts are defined as areas that receive less than 10 inches of rain per year. By that measure, Antarctica is actually the largest desert on Earth, occupying an area of about 5.5 million square miles, with the Arctic coming in second, at nearly 5.4 million square miles.

Read More: The Most Interesting Archaeological Finds Discovered in Antarctica

Yes, it seems weird that the Sahara should come in third in a desert-measuring contest, but there you have it. However, at 3.6 million square miles, the Sahara absolutely is the biggest hot desert in the world, by a wide margin: It’s more than three times the size of the next biggest desert (the Great Australian Desert) and almost quadruple the size of the Arabian Desert.

The name Sahara itself comes from the Arabic word for desert. The English word desert comes from the Latin desertum, denoting a place that is forsaken, uninhabited or without people. In fact, the Sahara is far from uninhabited. The desert is located mainly in northern Africa, spread across 10 different countries (11 if you include Western Sahara, a disputed territory) and is therefore home to as many as 2.5 million people.

Still, there’s no mistaking the fact that the Sahara Desert is, well, a desert. As such, it is one of the harshest environments on the planet. Large swaths of it are intensely harsh and inhospitable to life — human life, anyway.

Like many other deserts on the planet, the Sahara does indeed have Indigenous populations within its borders, including nomadic Arabs, Bedouins, and Berbers — one of the largest groups, which is historically made up of several different ethnic tribes, including the Tuareg.

Read More: Power to the People — By Plugging into the Sahara

While 2.5 million people sounds like a lot, bear in mind that most of those populations are clustered in cities and towns. Given the overall size of the Sahara, that number averages out to less than one person for every square mile of desert.

When you’re talking about an area of almost 4 million square miles, averages are not terribly representative, but for the record: the average depth of sand across the entire Sahara is about 16 feet.

The Sahara is certainly known for its sand dunes, which cover as much as a quarter of the desert. Those dunes can be as high as 600 feet, well above the average. That said, it’s important to remember that the Sahara actually has a varied landscape, including rocky areas and even mountains.

Like many deserts on Earth, the Sahara can broil you during the day and freeze you once the sun goes down. Yes, it surely is hot and dry, but the Sahara doesn’t hold claim to being the hottest place on Earth. Guinness World Records maintains that that distinction still belongs to Death Valley, California, where a high temperature of 134 degrees Fahrenheit was recorded in 1913.

Nevertheless, the Sahara is hot enough to make the average person rethink trekking across it without a seriously wide-brimmed hat and an awful lot of water. Research suggests that once you get above 104 degrees, the human body starts to function at less than optimum levels, with 122 degrees being the edge of what most humans can realistically withstand for any length of time. Depending on the location and the season, temperatures in the Sahara can get to as high as 117 degrees Fahrenheit in summer — a temperature that is almost literally baking. As if that wasn’t bad enough, once the sun goes down, you’ll stop baking and start dying from the cold: At night, the desert can get as bone-chillingly cold as 25 degrees Fahrenheit.

And yet life, as the saying goes, finds a way. Despite its challenging environment, the Sahara also supports a diverse range of plant and animal life. Estimates say that more than 500 different types of plants call the Sahara home, as do more than 250 different species of birds, mammals, reptiles, plus scorpions, spiders, and other tiny critters beyond counting.

Read More: These Rare Adaptations Help Animals Survive in the Desert

Some of the most well-known animals include, but are by no means limited to: antelopes, gazelles, camels, cheetahs, foxes and other wild dogs, ostriches and much, much more. Plant life, especially near water-rich oases, include olive, cypress, and palm trees, as well as a variety of grasses and other desert-adapted vegetable matter.

Although it gets as little as 3 inches of rain per year — way below what is required to be designated as a desert — the Sahara does still harbor several bodies of water. In fact, deep beneath the wastes of the Sahara, you'll find one of the planet’s largest reservoirs of underground water. The desert also holds nearly 100 significant oases that provide solace and shelter to both nomadic travelers and the many forms of life that have adapted to the desert wastes.

The truth is, the Sahara isn’t all that old. As little as 11,000 years ago, the Sahara wasn’t a desert at all, but a green and vibrant savannah that also included at least one massive lake. Indeed, the region used to be subject to annual monsoons, which naturally doused the land with plenty of moisture.

Alas, beginning around 4200 B.C.E. and continuing for another 2,000 years, the climate changed, the monsoons shifted south, the big lakes dried up (or went underground) and the area became much more arid. At least for now.

But in the future, climatologists predict that, as the axis of the Earth shifts (as it does from time to time), the now-desolate Sahara could once again become a lush grassland (as it does every 20,000 years or so), sustaining much more than the current meager life that it supports.

Read More: Swimming in the Sahara