Siwa
The Siwa Depression , 82 kilometers (51 miles ) long and between 9 to 28 kilometers (5.6 miles ) wide, is the furthest Egyptian Depression from the Nile Valley. There are several salt lakes in the depression, fed from sweer water underground springs. In the west are Birket al-Maraqi, 9 square kilometers (5.6 miles ) and Birket Siwa, the largest lake in the depression at 43 square kilometers ( 20 square miles ) . The only remaining lakes in the east are Birket Azmuri, and Birket Zaytun, a 16 square kilometer ( 10square mile) lake. In Siwa there are over 3000 mountains and hills. There are four important mountains in Siwa : Gebel al-Mawta , Gebel al-Dakrur, Gebel Hamra and Gebel Baydai. All the mountains are riddled with uninscribed caves. Siwa sits at the northwestern edge of the Great Sand Sea. There is plenty of water in Siwa, with over 1000 springs currently in use, but it is highly saline and not good for watering a wide variety of crops. Although the Siwans have a limited agriculture, growing only dates ( the best in all of North Africa ) , olives, and a few vegetables, still agriculture is the major industry in Siwa. The lakes are so salty that no marine life survives.