Atiu is a raised volcanic island surrounded by a reef from which rise 100-foot-high (30-metre) cliffs of fossilized coral (makatea).

Erosion of the inside of the ring has formed a dip of about 30 metres (98 feet) into fertile land, which gradually rises again to a central 70-metre-high (230-foot) flat-topped hill.

[5] Other traditions identify various settlers, including Te Ariki-Mou-Taua, Mariri, and Nuku-kere-i-manu, as well as a visit by the navigator Ruatapu.

Later that year John Williams of the London Missionary Society arrived and converted the island's leader, Rongomatane Ngaakaara Ariki, to Christianity.

On 12 March 2003, the population of Atiu was 571, in five villages radiating out from the island's centre, giving the appearance of a human figure.

In these houses they conduct village meetings and community functions like welcoming and feeding visitors, selling of products.

Educational courses are conducted in these houses and when a big group from overseas visit they could be accommodated in here for the time they are on the island.

There was once a custom on Atiu similar to that of New Zealand Māori of burying a newborn child's placenta under a newly planted tree.

[24] Following the collapse of the citrus industry and subsequent depopulation of the island, facilities are limited to a few shops, a lodge, and one motel.

On Atiu, under the supervision of New Zealand Resident Agent Ron Thorby and the Cook Islands Agriculture Department, new coffee plantations were established.

The poor financial return from selling their coffee to a Rarotongan company for processing had prompted the farmers to stop production except for their own private use.

[29] In 2012, the Atiu Coffee Factory managed 39 hectares (96 acres) of land and produced 4.5 tonnes of roasted beans.

[32] The pa tai (coast) and Rautuitui (upland makatea), are dominated by coconuts and Pandanus tectorius, with patches of Barringtonia asiatica, Elaeocarpus tonganus, and Hernandia moerenhoutiana.

[32] In 2017 the Moko‘ero Nui Nature Reserve was established on the western side of the island, protecting 120 hectares of coastal forest.

[34] Endemic birds include the Pacific imperial pigeon, chattering kingfisher, and lilac-crowned fruit dove.

[36] Because the island is free of black rats, it was chosen as a site for reintroduction of the Rarotonga monarch in 2001,[37] and Kuhl's lorikeet in 2007.