The islands are eroded volcanic tuff rings, and consist of a small northern pair on Upolu's barrier reef, and a larger southern pair outside it.

[3] From north to south, the islands consist of: Namua and Fanuatapu lie at the outer edge of the fringing reef of Upolu, at a distance of 0.7 km and 2.5 km, respectively, from Upolu Island itself.

The islands are uninhabited and relatively undisturbed, and provide an important refuge for native plant and animal species.

[2] The islands are home to the largest population of Tongan ground doves in Samoa, as well as Coconut crabs, and provides a nesting place for critically-endangered Hawksbill sea turtles,[4] and birds including the Samoan flycatcher and Manumean.

[1] In 2009 an attempt was made to eradicate the introduced Polynesian rat from the southern islands using air-dropped Brodifacoum to provide a pest-free refuge.