Michaelmas Island is an island located in King George Sound near Albany, Western Australia. The island is a nature reserve (declared in 1983) and managed by the Department of Environment and Conservation; its reserve number is 30049. The island is also registered as a national estate. The island is 91.9 hectares (227 acres) in area. Michaelmas Island has steep rocky shores with submerged reefs all along its northern southern and eastern sides in depths up to 30 metres (100 ft) with large granite boulders.