Dallas Reef, also known as Malay: Terumbu Laya; Vietnamese: đá Suối Cát; Mandarin Chinese: 光星礁; pinyin: Guāngxīng Jiāo; Rajah Matanda Reef, lies on the SW extremity of Dangerous Ground in the Spratly Islands of the South China Sea. It is approximately 7 km long and 2 km wide, and encloses a lagoon ~15m deep. Wikipedia