Khor Al Adaid, (Arabic: خور العديد; also spelled Khawr Al Udayd and Khor Al-‘Udeid) is a settlement and inlet of the Persian Gulf in Al Wakrah Municipality in southeast Qatar, on the border with Saudi Arabia. Approximately 78 kilometres (48 mi) south of the capital Doha, it is also known to local English speakers as the "Inland Sea". It formerly 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 designated as a major tourist destination for Qatar.
Khor Al Adaid was officially designated as a nature reserve by the Qatari government in 2007. Qatar has proposed the site's inclusion on the UNESCO World Heritage Site list, but as of 2025, it remains on UNESCO's Tentative List.
