| Great Sand Sea | |
| Native Name: | بحر الرمال العظيم |
| Native Name Lang: | ar |
| Settlement Type: | Desert |
| Subdivision Type: | Country |
| Subdivision Name: | Egypt and Libya |
| Area Total Km2: | 72000 |
| Elevation M: | 100 |
| Population Density Km2: | auto |
The Great Sand Sea is an approximately sand desert (erg) in the Sahara between western Egypt and eastern Libya in North Africa. Most of the area is covered by sand dunes.
The Great Sand Sea stretches about from north to south and from east to west. On satellite images this desert shows a pattern of long sand ridges running in a roughly north-south direction. However, despite the apparent uniformity the Great Sand Sea has two large areas with different types of megadunes.[1] The Egyptian sand sea lies parallel to the Calanshio Sand Sea of Libya, with which it is contiguous in the north. The dunes of the Great Sand Sea cover about 10% of the total area of the Egyptian Western Desert.
Siwa is an oasis located in Egypt, about east of the Libyan border, in the eastern part of the Great Sand Sea or Egyptian Sand Sea.
Although well-known to the Tuareg and traders who traveled with caravans across the Sahara, Friedrich Gerhard Rohlfs was the first European to document the Great Sand Sea. He began his Saharan expeditions in 1865, and named the great expanse of dunes the Große Sandmeer (Great Sand Sea), but it was not until 1924 with the maps of Ahmed Hassanein that the full scope of the Great Sand Sea was appreciated by Europeans.