The Houtman Abrolhos is made up of three main groups, the Wallabi, Pelsaert (or Southern) and the Easter groups. It is the most southern coral reef formation in the world, and has been the subject of intensive marine research. It scores very highly in terms of habitat diversity and species richness, with a unique blend of tropical and temperate species. It is also one of Australia's most important seabird breeding areas.
With 122 islands making up the chain, the sub-tropical reef is warmed by the Leeuwin Current. It serves as a major resource for the local fishing industry, and provides some of the best snorkeling, diving and deep sea fishing in the world, along with some of Australia's most significant historical sights, such as the shipwreck of the Batavia.