Ninth Island is an island in Bass Strait in south-eastern Australia. It is approximately 1.3 km long, 550 m wide and covers an area of 32 ha. It is part of the Waterhouse Island Group, lying 11.7 km from the north-eastern coast of Tasmania. It is partly privately owned and has been badly affected in the past by grazing, frequent fires and, in July 1995, by the MV Iron Baron oil spill which killed between 2000 and 6000 little penguins.