Western Desert

• 🌍 Bahariyya is the most accessible, five hours by bus from Cairo, and transport to other oases comes this way. Nearby there's a soot-black and a chalk-white desert to choose from.
• 🌍 Siwa far to the west is a large oasis, a county-sized fertile area some 20 km north-south by 50 km east-west, fed by a series of lakes and springs. Siwa town is the main settlement.
• 🌍 Farafra has sulfur springs, a few antiquities and is close to White Desert National Park.
• 🌍 Dakhla is another large oasis, some 25 km north-south by 80 km east-west. Main villages include Mut, El-Masara and Al-Qasr.
• 🌍 Kharga is the largest of all, 160 km north-south and up to 80 km east-west. This means it feels more like farmland than oasis, and Kharga the main town is modern, but with many nearby antiquities.

• 🌍 Gilf Kebir National Park — famous for its beautiful natural landscapes and prehistoric drawings on the cliffs and rock caves.
• 🌍 White Desert National Park —
• 🌍 Gabal El Uweinat — a mountain range at the Egyptian-Libyan-Sudanese tripoint with thousands of prehistoric rock art sites

To the ancient Egyptians the desert to the west signified death: it was where the sun god Ra went to die each day, and where the souls of the pharaohs went following their interment in tombs west of the life-giving Nile. But this desert contains five large oases, populated and cultivated since prehistory, and controlling trade routes.

A great aquifer of sandstone and limestone lies beneath the Western Desert, containing "fossil water" - rain that fell some 40,000 years ago, a non-renewable resource. In natural depressions (which are often extensive) this comes to the surface or is easily reached by wells. However these depressions have been scoured out by wind-blown sand and salt, and the water is only usable if it's not salty. The largest depression of all, Qattara, goes down to 147 m below sea level but its water is useless, so there's no oasis there. (In World War II it formed a natural defence for the British army, as its salt pans couldn't be crossed by vehicles.) The five oases all have salty water, sometimes entire bitter lakes, but enough fresh to sustain them. They are large fertile areas with towns and industry, and don't match the popular image of a few palm trees and huts clustered around a pool. For instance the aquifer at Siwa continues all the way into Libya, where it emerges as the Jaghbub oasis. They're all wildlife habitats eg for migratory birds, which gorge on the insects and grubs.

The Sahara is believed to alternate between fertile and desert over the 20,000 year cycle of the precession of the earth's axis of rotation, which alters the season of the North African Monsoon. So it turned to desert 5,000 years ago, leaving dried river beds with crocodiles in isolated pools, ruins among the sand dunes, and pushing migration and social change in pharaonic times. Unless disrupted by other climate change, it could again become savannah in another 15,000 years. But if the fossil waters are 40,000 years old, that's two cycles ago, suggesting that the latest "green" was poor, and so the next might be. In any case the water will be used up as quickly as Egypt's oil reserves unless tightly managed, and tourist resorts are notoriously profligate users of water. So there's a tension over how much development these oases can take.

One group of travellers who came to grief trying to get in was the army of Cambyses II, son of Cyrus the Great of Persia. Circa 534 BCE he faced rebellion in Egypt and dispatched a great army (which grows and grows in the telling) from Luxor towards Siwa. They vanished utterly. Herodotus a century later wrote that they were engulfed by desert sand storms. This seems unlikely, and no trace has ever been found, despite the capabilities of metal detectors and satellite photography. Perhaps they were heading somewhere else and people have looked in the wrong place. Perhaps they were a "ghost army" drawing pay and rations but with no real soldiers.

• By bus or long-distance taxi. There are no flights, and trains no longer run to Siwa or Kharga. For Siwa it's possible to take the train to Mersa Matruh on the coast, then a bus.

• Anywhere but Libya: this border is closed throughout.
• Back to the Nile at Cairo or Qena is the usual onward route, but from Siwa you can reach the Mediterranean coast at Mersa Matruh.