Flinders Island is an island in the Investigator Group off the coast of South Australia. It was named by Matthew Flinders after his younger brother Samuel Flinders, the second lieutenant on HMS Investigator in 1802. It is part of the Investigator Group Important Bird Area. The island has been subject to diamond exploration following the discovery of a wide range of kimberlite indicator minerals there. These minerals include chromite, pyrope, diopside, picroilmenite, forsterite, orthopyroxene, as well as small diamonds.