Saudi Arabia occupies about 80 percent of the Arabian peninsula, lying between latitudes 16o and 33o N, and longitudes 34o and 56o E. Because the country's southern borders with the United Arab Emirates and Oman are not precisely defined or marked, the exact size of the country remains unknown. The CIA World Factbook's estimate is 2,250,000 km2(868,730 sq mi) and lists Saudi Arabia as the world's 13th largest state.
Saudi Arabia's geography is dominated by the Arabian Desert and associated semi-desert and shrubland (see satellite image to right). It is, in fact, a number of linked deserts and includes the 647,500 km2(250,001 sq mi) Rub' al Khali ("Empty Quarter") in the southern part of the country, the world's largest contiguous sand desert. There are virtually no rivers or lakes in the country, but wadis are numerous. The few fertile areas are to be found in the alluvial deposits in wadis, basins, and oases. The main topographical feature is the central plateau which rises abruptly from the Red Sea and gradually descends into the Nejd and toward the Persian Gulf. On the Red Sea coast, there is a narrow coastal plain, known as the Tihamah parallel to which runs an imposing escarpment. The southwest province of Asir is mountainous, and contains the 3,133 m (10,279 ft) Mount Sawda, which is the highest point in the country.