Christmas Island is an island nature reserve, with an area of 63.49 ha, in south-eastern Australia. It is part of Tasmania’s New Year Island Group which includes the much larger King Island, lying north-west of Tasmania at the western limit of Bass Strait. According to the International Hydrographic Organization, the line separating Bass Strait from the Great Australian Bight runs through King Island, so Christmas Island lies in the Great Australian Bight.