Spratly Island, (Vietnamese: Đảo Trường Sa or Đảo Trường Sa Lớn, lit. 'the Big Spratly (Trường Sa) Island'; simplified Chinese: 南威岛; traditional Chinese: 南威島; pinyin: Nánwēi Dǎo; Filipino: Pulo ng Lagos, lit. 'Lagos Island'), also known as Storm Island, is the fourth largest of the naturally occurring Spratly Islands in the South China Sea with an area of 15 hectares (37 acres), and the largest of the Vietnamese-administered Spratly islands.

In 2016 the Vietnamese embarked on a land reclamation program at ten locations in the Spratly Islands. At Spratly Island 37 acres have been reclaimed, which has allowed for the addition of a harbour and the doubling of the length of the island's runway to a length of about 4,000 feet (1,200 m).

It is also claimed by China (PRC) and Taiwan (ROC).