Qatar is a peninsula in the east of Arabia, bordering the Persian Gulf and Saudi Arabia, in a strategic location near major petroleum deposits. Qatar occupies 11,437 km² (4,416 sq mi) on a peninsula that extends approximately 160 km (99 mi) north into the Persian Gulf from the Arabian Peninsula. Varying in width between 55 and 90 km (34 and 56 mi), the land is mainly flat (the highest point is 103 m (338 ft)) and rocky. Notable features include coastal salt pans, elevated limestone formations (the Dukhan anticline) along the west coast under which lies the Dukhan oil field, and massive sand dunes surrounding Khawr al Udayd, an inlet of the Persian Gulf in the southeast known to local English speakers as the Inland Sea. Of the islands belonging to Qatar, Halul is the most important. Lying about 90 km (56 mi) east of Doha, it serves as a storage area and loading terminal for oil from the surrounding offshore fields.