Tunisia's climate is Mediterranean in the north, with mild rainy winters and hot, dry summers. The south of the country is desert. The terrain in the north is mountainous, which, moving south, gives way to a hot, dry central plain. The south is semiarid, and merges into the Sahara. A series of salt lakes, known as chotts or shatts, lie in an east-west line at the northern edge of the Sahara, extending from the Gulf of Gabes into Algeria. The lowest point is Chott el Djerid at below sea level and the highest is Jebel ech Chambi at .