As-Suman

Al-Suman is a broad limestone plateau between the sands of ad-Dahna and the Gulf coastal plain. Its surface is broken by shallow depressions that collect rainwater and by deep natural openings known as dahls. Hundreds of sinkholes mark the plateau, some leading into cave systems. Beneath al-Suman lies the Umm er Radhuma aquifer, a source of groundwater in eastern Arabia.