Timor-Leste is a coastal State in Southeast Asia, northwest of Australia and at the eastern end of the Indonesian archipelago.

To the east, north and west, Timor-Leste’s maritime neighbour is Indonesia, the largest archipelagic State in the world.

To the south lies Timor-Leste’s other great neighbour, Australia, which has one of the largest maritime areas in the world. Timor-Leste and Australia face each other across the Timor Sea, about 250 nautical miles apart at the closest point and nowhere more than 400 nautical miles apart. The physical continental shelf in the Timor Sea is very shallow for over 200 nautical miles from the northern Australian landmass until it reaches the deep and narrow Timor Trough. This part of the shelf is known as the Bonaparte Basin, a major sedimentary basin and a highly prospective zone which includes the Sunrise and Troubadour gas-condensate deposits (together known as Greater Sunrise).

A brief history of Timor-Leste’s struggle for maritime boundaries

The Timor Sea has been the subject of commercial interest for decades due to its vast reserves of oil and gas resources.

Before the restoration of Timor-Leste’s independence in 2002, while the country was under occupation by Indonesia, Australia and Indonesia negotiated an arrangement in the area of the Timor Sea between Timor-Leste and Australia known as the ‘Timor Gap’ to share revenue from resources extracted within an area they called the ‘Zone of Cooperation’. This agreement, known as the Timor Gap Treaty, provided substantial benefits to Australia beyond the entitlements it would otherwise have under international law.

In March 2002, two months before Timor-Leste restored its independence, Australia ‘carved-out’ maritime boundary disputes from the binding jurisdiction of the International Court of Justice, the International Tribunal for the Law of the Sea and other dispute resolution bodies under UNCLOS. Under international law, unlike domestic law, States need to accept the jurisdiction of international bodies and agree to be bound by any decisions made by them before another State can ask these bodies to resolve a dispute.

This meant that Timor-Leste was not able to ask an international court or tribunal to give a binding determination on its permanent maritime boundary with Australia.

The Australian Government also declined Timor-Leste’s invitations to negotiate maritime boundaries.

Read more about Timor-Leste’s Maritime Boundaries here



This website is hosted by the Maritime Boundary Office of the Council for the Final Delimitation of Maritime Boundaries to allow readers to learn more about Timor-Leste’s pursuit of permanent maritime boundaries. The Council for the Final Delimitation of Maritime Boundaries and the Maritime Boundary Office do not accept any legal liability for any reliance placed on any information contained in this website (including external links). The information provided is a summary only and should not be relied upon as legal advice. The information and views expressed in this website and in any linked information do not constitute diplomatic representations and do not limit or otherwise affect the rights of the Council for the Final Delimitation of Maritime Boundaries, the Maritime Boundary Office or the Government of Timor-Leste. The views expressed in any linked information do not necessarily reflect the views of the Council for the Final Delimitation of Maritime Boundaries, the Maritime Boundary Office or the Government of Timor-Leste.

GFM is the acronym for “Gabinete das Fronteiras Marítimas”, which is the Portuguese translation of Maritime Boundary Office.


A group of islands and interconnecting waters which are so close to each other so as to be considered to be a single entity, such as Indonesia.

Timor Trough

The geological formation where the seabed south of Timor-Leste drops sharply and forms a trough or a trench.

Timor Gap

The gap between the points A16 and A17 in the Timor Sea created by the 1972 Australia-Indonesia maritime boundary. The Joint Petroleum Development Area, which was created under the Timor Sea Treaty between Australia and Timor-Leste, is roughly located within this ‘gap’.