The Tubuai Islands (Îles Australes/Austral Islands) are a long chain of remote islands located in the far South Pacific. The islands lie southwest from the Cook Islands (325 km northwest from Îles Maria) and 550 km south from the Society Islands. In all there are 7 main islands (with a combined land area of 148 km²) within the 1,300 km-long, northwest to southeast orientated, chain.
Five of the islands are inhabited — Raivavae (16 km²), Rapa (40 km²), Rimatara (8.6 km²), Rurutu (29 km²), and Tubuai (45 km²). The group also includes the uninhabited atoll of Maria (1.4 km²) and the rocky peaks of Marotiri (Îlots de Bass, 43.1 ha).
The islands are the remains of former volcanic peaks, thought to been have formed over a hot-spot, in much the same way as the Hawaiian Islands. The islands at the southeast end of the chain are geologically the youngest — the Îles Marotiri (Îlots de Bass) are a tight cluster of 4 rocky islands and emergent rocks whose steep slopes support a scant vegetation. Maria, the most northeasterly of the islands is the oldest of the Tubuai Islands. Its former volcanic peak has long since disappeared, but coral growth has kept this last remnant above sea level, surviving as an atoll formation. Islands in the middle of the chain have a more complex geological history — uplift processes and changing sea levels at islands such as Rimitara and Rurutu have exposed once submerged fringing reefs, creating low limestone ridges around these islands.