Informal:
* Oz: This is a common nickname for Australia.
* The Land Down Under: This is a popular and poetic phrase.
* Down Under: This is a shorthand for "The Land Down Under."
Formal:
* The Commonwealth of Australia: This is the official name of the country.
* The Australian Continent: This emphasizes Australia's status as a continent.
Other:
* The Outback: This refers to the remote and sparsely populated interior of Australia.
* The Southern Hemisphere: This is a broad term, but Australia is a major part of it.
The best alternative will depend on the specific context and the tone you're trying to achieve.