Nukunonu, Coral atoll in Tokelau, South Pacific Ocean.

Nukunonu is the largest atoll of Tokelau, a New Zealand dependency in the South Pacific. Its 30 islets enclose a central lagoon of 109 km2, while the land totals about 5.5 km2. The main settlement sits on Nukunonu Island at the southwestern edge of the lagoon, and a concrete bridge links its two built-up areas.

A British ship discovered the atoll in 1791 and named it after a British nobleman. The islands remained difficult to reach and stayed relatively isolated for a long time.

Local administration rests with the Taupulega, a Council of Elders made up of heads of family groups and two elected members. More than 95% of residents belong to the Catholic Church, converted by Samoan missionaries in the early 19th century, and the atoll hosts the administration of the Sui iuris Catholic mission.

The atoll has no proper anchorage facilities, making deliveries and supply difficult to arrange. Visitors should be prepared for limited accessibility, as boats may not always be able to dock.

About 60 hectares on the eastern side of the atoll form an Important Bird Area designated by BirdLife International. In 2011 an estimated 20,000 breeding pairs of brown noddies, black noddies and common white terns nested there.