Sand Cay, also known as Bailan Island (Filipino: Pulo ng Bailan) and Son Ca Island (Vietnamese: Đảo Sơn Ca; Mandarin Chinese: 敦謙沙洲/敦谦沙洲; pinyin: Dūnqiān Shāzhōu), is a cay on the north edge of the Tizard Bank of the Spratly Islands in the South China Sea. With an natural area of 7 hectares (17 acres), it is the ninth largest, and the fourth largest Vietnamese-administered, of the Spratly Islands. The island has been occupied by Vietnam since 1974 (first by South Vietnam, then by the Socialist Republic of Vietnam after 1975). It is also claimed by China (PRC), the Philippines, Vietnam, and Taiwan (ROC). According to reports for 2025, Vietnam expanded the island to 40 hectares with land reclaimed from the sea.