Australia’s International Maritime Boundaries

The outer edge of Australia’s Exclusive Economic Zone (EEZ) is 200 nautical miles from Australia's territorial sea baseline, other than in areas subject to delimitation with neighbouring countries. In those areas, the location of the outer edge of the EEZ will depend on the EEZ boundary agreed in the treaty between Australia and the relevant country.

Australia has entered into maritime boundary treaties with Indonesia, Timor-Leste, Papua New Guinea, Solomon Islands, New Zealand and France (New Caledonia and Kerguelen).

Particularly relevant to offshore petroleum exploration are the treaties between Australia and Timor-Leste and Australia and Indonesia.

A map of Australia’s maritime boundaries can be found at:

Australia-Timor-Leste maritime boundaries

Australia and Timor-Leste are yet to delimit their maritime boundaries but have committed to negotiate permanent maritime boundaries under the auspices of the Conciliation Commission constituted under the United Nations Convention on the Law of the Sea as part of an integrated package of measures agreed by both countries.

Pending the conclusion of a permanent maritime boundary the Parties have agreed that the Timor Sea Treaty between the Government of East Timor and the Government of Australia 2002 [2003] ATS 13 (the TST) and the regulatory framework that it established for the joint management and development of hydrocarbon resources within the Joint Petroleum Development Area (JPDA) continues to apply. Further information on the TST is provided below.

Australia-Indonesia maritime boundaries

Australia and Indonesia have entered into a number of agreements and arrangements relating to the maritime area between Australia and Indonesia including the area between the Australian Territory of Christmas Island and the Indonesian island of Java, These include:

Figure 1: Consolidated Maritime Boundary Treaties between Australia and Indonesia and the 1974 MoU

Consolidated Maritime Boundary Treaties between Australia and Indonesia

Perth Treaty

The 1971 and 1972 seabed agreements that are in force, establish a seabed boundary between Australia and Indonesia across much of the Arafura and Timor Seas. The Perth Treaty, signed by Australia and Indonesia in 1997, establishes an EEZ boundary and certain seabed boundaries.

Under the 1997 Perth Treaty, there are areas of overlapping jurisdiction where Australia exercises seabed jurisdiction including to explore for petroleum, and Indonesia exercises water column jurisdiction including fishing rights (the Perth Treaty area).

While the Perth Treaty has yet to enter into force, the Australian Government acts consistently with its obligations under the Perth Treaty pending its entry into force. The Perth Treaty sets out a number of obligations, including:

  • Article 7 - Areas of overlapping jurisdiction: requires that Australia give Indonesia three months’ notice of ‘the proposed grant of exploration or exploitation rights’ in the Perth Treaty area.

  • Article 9 - Exploitation of certain seabed deposits: directs the Parties to seek agreement on the most effective means of exploiting and equitably sharing any hydrocarbon deposit that straddles the maritime boundaries described in the treaty.

Under Article 7, notification to Indonesia is undertaken:

  • At least three months prior to the proposed grant of exploration and exploitation rights in the Perth Treaty area.

  • Prior to the construction of any installations or structures in the Perth Treaty area.

The notification process is conducted by the Australian Government Department of Industry, Innovation and Science through the Attorney-General’s Department and the Department of Foreign Affairs and Trade, who liaise directly with the Indonesian Government in Jakarta. Explorers should familiarise themselves with the various treaties and understand any implications for investments.

Indonesian Traditional Fishing in the ‘MoU Box’

The 1974 Australia-Indonesia Memorandum of Understanding regarding the Operations of Indonesian Traditional Fishermen in Areas of the Australian Exclusive Fishing Zone and Continental Shelf (the MOU) provides a basis for traditional Indonesian fishing access to an area defined as the ‘MOU Box’ within Australia’s north-western exclusive economic zone. Specifically, Australia agrees to refrain from applying its fisheries laws against traditional Indonesian fishermen who conduct their operations in accordance with the MOU.

Traditional fishers can be found in any part of the dedicated MOU Box and in adjacent Australian waters where they may stray from time to time. Their vessels are likely to have ‘longlines’ of 1-2 km long deployed and diving is also known to occur. The traditional fishermen may not carry communication equipment and they are not known to use navigation lights or radar reflectors. The vessels are not motorised which limits their capacity to take evasive action. The hulls are timber and present poor radar targets.

Indonesian fishermen target some species that are sedentary that at the harvestable stage, are either immobile on or under the seabed, or are unable to move except in constant physical contact with the seabed or the subsoil. This includes trochus, beche de mer, abalone, green snail, sponges and molluscs.

Based on these facts, caution is recommended when operating in the MOU Box.

Australia and Timor-Leste Joint Petroleum Development Area

The Joint Petroleum Development Area (JPDA) is situated in the Timor Sea between Australia and Timor-Leste. It was established by the TST that provides the framework for all petroleum exploration and development within the JPDA. The TST is one of the provisional arrangements that is without prejudice to the position of either country on their maritime boundary claims.

The TST provides that title to petroleum production in the JPDA is split between Timor-Leste and Australia on a 90:10 basis.

The TST creates the Joint Commission to establish policies and regulations for petroleum activities in the JPDA and to oversee the work of the Designated Authority. The Joint Commission is comprised of one Australian representative and two Timorese representatives.

Day-to-day regulation and management of the JPDA is the responsibility of the Designated Authority that is currently the Timor-Leste offshore regulator, the Autoridade Nacional do Petróleo (ANP). The ANP regulates operations in the JPDA on behalf of both countries.

Further information on developments within the JPDA, including revenue received by both Timor-Leste and Australia, is available from the ANP website at