The Southwest Australia Biodiversity Hotspot occupies some 356,700 square kilometers of the southwestern tip of the continent. Most rain falls during the winter months and the summers are characteristically dry. Native plants are well adapted to the nutrient-poor soils, which also support large-scale crop operations and sheep grazing.

Principal vegetation types in this region are Eucalyptus woodlands, and the Eucalyptus-dominated "mallee" shrubland. Kwongan is a term adapted from the Aboriginal Noongar language to cover the various Western Australian types of shrubland,

The forest, woodlands, shrublands and heath of the hotspot are characterized by high endemism among plants and reptiles. Its vertebrate species include the Endangered numbat (Myrmecobius fasciatus) and honey possum (Tarsipes rostratus)—both marsupials—and the stunning red-capped parrot (Purpureicephalus spurius).

The Critically Endangered western swamp turtle (Pseudeudemydura umbrina), which is dormant for nearly eight months of the year in response to dry conditions and hot temperatures, is among the most threatened freshwater turtle species in the world.