Nanumanga is not a tourist destination — there are no organised sights and no facilities. The interest is in walking the island, sitting in the maneapa at Tokelau, and exploring the two inland lagoons of Vaiatoa and Ha'apai.
The most famous feature is offshore: the submerged Caves of Nanumanga, where divers in 1986 reported finding what they took to be prehistoric fire pits. Visiting requires permission from the island council and serious diving experience. Even the reef passage where boats land is worth attention — Nanumanga has no lagoon and the open-ocean transfer is part of the experience.