Khor al Udaid, (also spelled Khawr al Udayd and Khor al-‘Udeid) is a settlement and inlet of the Persian Gulf located in Al Wakrah Municipality in southeast Qatar, on the border with Saudi Arabia. It is known to local English speakers as the "Inland Sea". In the past it accommodated a small town and served as the center of a long-running territorial dispute between Sheikh Jassim bin Mohammed Al Thani and Sheikh Zayed bin Khalifa Al Nahyan. At the present, it is a major tourist destination for Qatar.
The area was declared a nature reserve in 2007. Qatar has pitched Khawr al Udayd's potential inclusion as a World Heritage Site to UNESCO but it currently only occupies the Tentative List.
The area of Khawr al Udayd had been a point of friction between Qatar and what is now Saudi Arabia and the United Arab Emirates (UAE). Khawr al Udayd had served as a refuge for pirates from the Emirate of Abu Dhabi (now part of the UAE) during the 19th century. Members of the Bani Yas tribe migrated and settled in the area on three separate occasions: 1835, 1849 and 1869. According to a historical overview of Khawr al Udayd written by the British government in India, "in 1836, Al-Kubaisat, a section of the Bani-Yas, under Sheikh Khadim-bin-Nahman, being desirous of avoiding the consequences of certain recent piracies, seceded from Abu Dhabi and established themselves at Odeid In 1849, there was a fresh secession, followed by a second compulsory return; at length, in 1869, a party under Sheikh Buttye-bin-Khadim again settled at Odeid, and repudiated their allegiance to the parent State.