C21 – Nauru, officially the Republic of Nauru (Nauruan: Repubrikin Naoero) and formerly known as Pleasant Island, is an island country in Micronesia, a subregion of Oceania, in the Central Pacific.

Its nearest neighbour is Banaba Island in Kiribati, 300 km (190 mi) to the east. It further lies northwest of Tuvalu, 1,300 km (810 mi) northeast of the Solomon Islands, east-northeast of Papua New Guinea, southeast of the Federated States of Micronesia and south of the Marshall Islands.

With only a 21 km2 (8.1 sq mi) area, Nauru is the third-smallest country in the world behind the Vatican City, and Monaco, making it the smallest state in the South Pacific Ocean, the smallest state outside Europe, the smallest island state, and the smallest republic.