Australia–Indonesia border

The Australia–Indonesia border is a maritime boundary running west from the two countries' tripoint maritime boundary with Papua New Guinea in the western entrance to the Torres Straits, through the Arafura Sea and Timor Sea, and terminating in the Indian Ocean. The boundary is, however, broken by the Timor Gap, where Australian and East Timorese territorial waters meet and where the two countries have overlapping claims to the seabed.

Australia and Indonesia also share a common maritime border in the Indian Ocean between Australia's overseas territory of Christmas Island and the Indonesian island of Java.

A characteristic of the maritime border between the two countries is the separation of the ownership of the seabed (essentially the continental shelf) and ownership of the water column (exclusive economic zone), each with its own boundary. Ownership of the seabed gives the country rights over all mineral resources in the seabed while ownership of the water column allows a country fishing rights and rights to other resources of the water in the specified area. The 1997 treaty establishing this and the western parts of the border, as well as that between Christmas Island and Java, has however not been ratified and is not in force. This was because the independence of East Timor required amendments to the 1997 treaty and agreement over them by the two parties is still pending.