Atafu, formerly known as the Duke of York Group, is a group of 42 coral islets within Tokelau in the south Pacific Ocean, 500 kilometres (310 miles) north of Samoa. Covering 2.5 square kilometres (1.0 square mile), it is the smallest of the three islands that constitute Tokelau, and is composed of an atoll surrounding a central lagoon, which itself covers some 15 km². The atoll lies some 800 kilometres (500 miles) south of the equator at 8° 35' South, 172° 30' West.