900,000 square kilometers

Photo from Wikimedia Commons
Kalahari Desert
The great thirstland of southern Africa/Deserts
The Kalahari Desert spans about 900,000 square kilometers across Botswana, Namibia, and South Africa. Despite being called a desert, it receives more rainfall (200-500 mm per year) than true deserts and supports considerable wildlife, including the famous Kalahari lions, meerkats, and the San (Bushmen) people who have inhabited it for 20,000 years. The Kalahari is covered in reddish sand, with the Okavango Delta forming a remarkable inland oasis where the Okavango River empties into the desert and evaporates.
Measurements
From Democratic Republic of Congo to South Africa
Maximum width
Above sea level
About 45 degrees C in summer
Maximum depth of sand deposits