Swallow Reef, also known as Malay: Pulau Layang-Layang; Vietnamese: Đá Hoa Lau; Mandarin Chinese: 燕子島; pinyin: Yànzi Dǎo; Celerio Reef (Filipino: Bahura ng Celerio), is an oceanic atoll of the Spratly Islands administered by Malaysia.

The Royal Malaysian Navy (RMN) has maintained a presence on the reef since 1983, but as with all of the Spratly Islands, the ownership is disputed, and it is also claimed by the People's Republic of China, the Republic of China (Taiwan) and Vietnam. The Philippines does not lay claim to Swallow Reef.