The archipelago consists of about 10 islands within an approximate 60 km radius. They sit on the Chatham Rise, an undersea plateau.
Some of the islands, formerly cleared for farming, are now preserved as nature reserves to conserve some of the unique flora and fauna. The islands are home to a rich biodiversity including about 50 endemic plants. The islands are a breeding ground for huge flocks of seabirds and are home to a number of endemic birds, some of which are seabirds and others which live on the islands. Many species of marine mammals are attracted to the rich food sources of the Chatham Rise.