Western Australia is a state of Australia occupying the western third of the land area of Australia, excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Australia is Australia's largest state, with a total land area of 2,527,013 square kilometres (975,685 sq mi). It is the second-largest country subdivision in the world, surpassed only by Russia's Sakha Republic. As of 2021, the state has 2.76 million inhabitants—11 percent of the national total. The vast majority live in the south-west corner; 79 percent of the population lives in the Perth area, leaving the remainder of the state sparsely populated.

The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of 20,327,000 km2 (7,848,000 sq mi), it is regarded as the second-smallest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian oceans but larger than the Arctic Ocean.