Australia is bordered by:
In addition, there are numerous seas. See the related question.
The Southern Ocean, also known as the Great Southern Ocean, borders Australia's southern coastline.
The Pacific ocean.
The Indian Ocean borders Australia's western coastline.
The Pacific Ocean
The Indian Ocean border Australia's Western coastline, while the Southern Ocean borders the southwest.
The Indian Ocean borders the western coastline of Australia.
The Indian Ocean
The Indian Ocean Indian Ocean IT'S THE INDIAN OCEAN!
The Indian Ocean borders Australia's western coastline, as well as the northwestern coast The Timor Sea is the branch of the Indian Ocean which meets the northwestern coast.
Australia
The Indian Ocean I believe.
To the west, the Indian Ocean touches (not borders) Australia's coastline. To the east, it is the Pacific Ocean. Three seas border Australia's northern coastline: the Timor Sea, the Arafura Sea and the Coral Sea.