Macclesfield Bank is an elongated sunken atoll of underwater reefs and shoals in the South China Sea. It lies east of the Paracel Islands, southwest of the Pratas Islands and north of the Spratly Islands. Its length exceeds 130 km (81 mi) southwest-northeast, with a maximal width of more than 70 km (43 mi). With an ocean area of 6,448 km² (2,490 sq mi) within the outer rim of the reef, although completely submerged without any emergent cays or islets, it is one of the largest atolls of the world.