Timor Sea

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Timor Sea
The Timor Sea at Vessoru, East Timor
Locatie Timorzee.PNG
Location of the Timor Sea
LocationEastern Indian Ocean, Asia, Oceania
Coordinates 10°S127°E / 10°S 127°E / -10; 127
Type Sea
Native name
Etymology Timor Island
Part of Indian Ocean
Ocean/sea sourcesIndian Ocean
Basin  countries
Surface area610,000 km2 (240,000 sq mi)
Average depth406 m (1,332 ft)
Max. depth3,300 m (10,800 ft)
Islands Ashmore and Cartier Islands, Browse Island, Tiwi Islands
Trenches Timor Trough
Settlements Darwin, Northern Territory

The Timor Sea (Indonesian : Laut Timor, Portuguese : Mar de Timor, Tetum : Tasi Mane or Tasi Timór) is a relatively shallow sea in the Indian Ocean bounded to the north by the island of Timor with Timor-Leste to the north, Indonesia to the northwest, Arafura Sea to the east, and to the south by Australia. The Sunda Trench marks the deepest point of the Timor Sea with a depth of more than 3300 metres, separating the continents of Oceania in the southeast and Asia to the northwest and north. The Timor sea is prone to earthquakes and tsunamis north of the Sunda Trench, due to its location on the Ring of Fire as well as volcanic activity and can experience major cyclones, due to the proximity from the Equator.


The sea contains a number of reefs, uninhabited islands and significant hydrocarbon reserves. International disputes emerged after the reserves were discovered resulting in the signing of the Timor Sea Treaty.

The Timor Sea was hit by the worst oil spill for 25 years in 2009. [1]

It is possible that Australia's first inhabitants crossed the Timor Sea from the Malay Archipelago at a time when sea levels were lower.[ citation needed ]


The Timor Sea is named after Timor, the island on the other side of the sea's northern coastline. [2] The island's name is a variant of timur, Malay for "east".

In Tetum, the sea is often referred to by the expression tasi mane (lit. transl.'male sea'). The counterpart of that body of water, the 'Ombai-Wetar Strait', which has smaller waves, is less turbid, and washes most of Timor island's northern shores, is commonly referred to in Tetum as tasi feto (lit. transl.'female sea'). [3]


Timor Sea and neighbouring seas Timor See.jpg
Timor Sea and neighbouring seas

The waters to the east are known as the Arafura Sea. The Timor Sea is adjacent to three substantial inlets on the north Australian coast, the Joseph Bonaparte Gulf, Beagle Gulf and the Van Diemen Gulf. The Australian city of Darwin which is located in part on the shore of the Beagle Gulf, is the nearest large city to the sea. [4] The small town of Wyndham is located on the west arm of Cambridge Gulf, an inlet of Joseph Bonaparte Gulf.

Rivers that enter the Timor Sea from the Northern Territory include Fish River, King River, Dry River, Victoria River and the Alligator Rivers. Rivers in the Kimberley region that flow into the Timor Sea include the Ord River, Forrest River, Pentecost River and Durack River.

The sea is about 480 km (300 mi) wide, covering an area of about 610 thousand km2 (240,000 sq mi). Its deepest point is the Timor Trough (which some geologists consider is the south-eastern extension of the Java Trench, but others view as a foreland trough to the Timor Island "mountain range"), located in the northern part of the sea, which reaches a depth of 3,300 m (10,800 ft). The remainder of the sea is much shallower, much of it averaging less than 200 m (660 ft) deep, as it overlies the Sahul Shelf, part of the Australian continental shelf.

The Big Bank Shoals is an area on the sloping seabed between the continental shelf and the Timor Trough where a number of submerged banks are located. [5] The ecosystem of the shoals differs significantly from the deeper waters surrounding them. In May 2010, it was announced that a crater about 50 km (31 mi) wide has been discovered on the seabed of the Timor Sea. [6]


Tropical cyclone Floyd over the Timor Sea, 2006 TC Floyd 22 mar 2006 0235Z.jpg
Tropical cyclone Floyd over the Timor Sea, 2006

The International Hydrographic Organization (IHO) defines the Timor Sea as being one of the waters of the East Indian Archipelago. The IHO defines its limits as follows: [7]

On the North The Southeastern limit of the Savu Sea [By a line from the Southwest point of Timor to the Northeast point of Roti, through this island to its Southwest point] the Southeastern coast of Timor and the Southern limit of the Banda Sea [A line from Tanjong Aro Oesoe, through Sermata to Tanjong Njadora the Southeast point of Lakov ( 8°16′S128°14′E / 8.267°S 128.233°E / -8.267; 128.233 ) along the South coasts of Lakov, Moa and Leti Islands to Tanjong Toet Pateh, the West point of Leti, thence a line to Tanjong Sewirawa the Eastern extremity of Timor].

On the East. The Western [limit] of the Arafura Sea [A line from Cape Don to Tanjong Aro Oesoe, the Southern point of Selaroe (Tanimbar Islands)].

On the South. The North coast of Australia from Cape Don to Cape Londonderry ( 13°47′S126°55′E / 13.783°S 126.917°E / -13.783; 126.917 ).

On the West. A line from Cape Londonderry to the Southwest point of Roti Island ( 10°56′S122°48′E / 10.933°S 122.800°E / -10.933; 122.800 ).


Many tropical storms and cyclones originate or pass through the Timor Sea. In February 2005, Tropical Cyclone Vivienne disrupted oil and gas production facilities in the area, and the next month, Severe Tropical Cyclone Willy interrupted production.[ citation needed ] Petroleum production facilities are designed to withstand the effects of cyclones, although as a safety precaution production work is often reduced or temporarily halted and workers evacuated by helicopter to the mainland - usually to Darwin or Dili.

Reefs and islands

August 2005 NASA satellite photograph of the Rowley Shoals ESC large ISS005 ISS005-E-15298.JPG
August 2005 NASA satellite photograph of the Rowley Shoals

A number of significant islands are located in the sea, notably Melville Island, part of the Tiwi Islands, off Australia and the Australian-governed Ashmore and Cartier Islands. It is thought that early humans reached Australia by "island-hopping" across the Timor Sea.

Scott and Seringapatam Reefs formed in the area and to the west, on the same underwater platform, are the Rowley Shoals.


World War II

During the 1940s the Japanese navy conducted air raids on Australia from ships in the Timor Sea. On the 19 February 1942 the Japanese aircraft carrier Kaga with other vessels, launched air strikes against Darwin, Australia, sinking nine ships, including the USS Peary . This bombing marked the beginning of the Battle of Timor in the Pacific theatre of World War II.


Timor Current

The Timor Current is an oceanic current that runs south-west in the Timor Sea between the Malay Archipelago and Australia. It is a major contributor to the Indonesian Throughflow that transports water from the Pacific Ocean to the Indian Ocean.

Hydrocarbon reserves

Oil slick from the Montara oil spill in the Timor Sea September 2009. Oil Slick in the Timor Sea September-2009.jpg
Oil slick from the Montara oil spill in the Timor Sea September 2009.
Big John Big John.tif
Big John

Beneath the Timor Sea lie considerable reserves of oil and gas. Confirmation of the prospectivity of the Timor Sea came when Woodside-Burmah's Big John rig drilled Troubadour No. 1 well in June 1974 on the Troubadour Shoals about 200 kilometres (120 mi) southeast of Timor, and intersected 83 metres (272 ft) of hydrocarbons. A number of offshore petroleum projects are in operation and there is considerable exploration activity either underway and numerous proposed projects. A gas pipeline crosses the Timor Sea from the Joint Petroleum Development Area to Wickham Point near Darwin. [8]

The Timor Sea was the location for Australia's largest oil spill when the Montara oil field leaked oil, natural gas and condensate from 21 August to 3 November 2009. [9] During the spill 400 barrels (64 m3) of oil leaked each day. The Montara Commission of Inquiry placed blame on the Thai company PTTEP, owner of the wells. [1]

Bayu-Undan project

The largest petroleum project in operation in the Timor Sea is the Bayu-Undan project operated by Santos. [10] The Bayu-Undan field is located approximately 500 km (310 mi) north-west of Darwin in the Bonaparte Basin. [11] Production commenced in 2004 as a gas recycle project - with liquids (condensate, propane and butane) being stripped from the raw production stream and exported. Gas was pumped back down into the reservoir. At around the same time, construction commenced on a 500 km (310 mi) subsea natural gas pipeline connecting the Bayu-Undan processing facility to a liquefied natural gas plant situated at Wickham Point in Darwin harbour. Since the completion of the pipeline and the Darwin LNG plant in 2005, gas produced offshore at Bayu-Undan is now transported to the Darwin plant where it is converted into a liquid and transported to Japan under long-term sales contracts. [12] Timor-Leste has made, as of 2017, over $18 billion from Bayu-Undan since production began; however, it is predicted its reserves will be exhausted by 2023. [13]

Ichthys gas field

The Ichthys gas field is a natural gas field located in the Timor Sea, off the northwestern coast of Australia. The field is located 220 km offshore Western Australia and 820 km southwest of Darwin, with an average water depth of approximately 250 metres. [14] It was discovered in 2000. First Gas from the Ichthys field was achieved on 30 July 2018. [15]

Other projects

AED Oil owns the large oil project at Puffin oilfield and Woodside Petroleum is producing oil at the Laminaria oilfield. The Greater Sunrise gas field, discovered in 1974, is one of the largest in the area and is expected to earn East Timor several billion dollars in royalty revenues. Woodside Petroleum plans to process gas from Greater Sunrise via a floating platform, however Xanana Gusmão, East Timor's Prime Minister opposes this plan and instead wants the gas to go to Beaço via a pipeline for processing. [16]

Territorial dispute

Demonstration against Australia in December 2013 Oil demo Timor 2013.JPG
Demonstration against Australia in December 2013

Since the discovery of petroleum in the Timor Sea in the 1970s, there have been disputes surrounding the rights to ownership and exploitation of the resources situated in a part of the Timor Sea known as the Timor Gap, which is the area of the Timor Sea which lies outside the territorial boundaries of the nations to the north and south of the Timor Sea. [17] These disagreements initially involved Australia and Indonesia, although a resolution was eventually reached in the form of the Timor Gap Treaty. After declaration of East Timor's nationhood in 1999, the terms of the Timor Gap Treaty were abandoned and negotiations commenced between Australia and East Timor, culminating in the Timor Sea Treaty.

From 1965 to 2018, Australia's territorial claim extended to the bathymetric axis (the line of greatest sea-bed depth) at the Timor Trough. It overlapped East Timor's own territorial claim, which followed the former colonial power Portugal and the United Nations Convention on the Law of the Sea in claiming that the dividing line should be midway between the two countries. In 2018, Australia agreed to a median line boundary.

It was revealed in 2013 that the Australian Secret Intelligence Service (ASIS) planted listening devices to listen to East Timor during negotiations over the Greater Sunrise oil and gasfields. This is known as the Australia–East Timor spying scandal.

Timor Sea Treaty

The Timor Sea Treaty, which was signed on the 20 May 2002, led to the establishment of the Timor Sea Designated Authority (TSDA). This organisation is responsible for the administration of all petroleum-related activities in a part of the Timor Sea known as the Joint Petroleum Development Area (JPDA). The treaty was ratified in February 2007. [17]

Under the terms of the treaty, royalties on petroleum production in the JPDA are split in a 90:10 ratio between East Timor and Australia. [18] It has been criticised because the treaty did not finalise the maritime boundary between East Timor and Australia. [17]

2018 Maritime Boundaries Treaty

The Australia–Timor Leste Treaty Establishing Their Maritime Boundaries in the Timor Sea was signed on 6 March 2018 at United Nations headquarters in New York in the presence of United Nations Secretary-General Antonio Guterres. [19]

See also

Related Research Articles

<span class="mw-page-title-main">Geography of East Timor</span> Geographical features of East Timor

The geography of East Timor exhibits a mountainous terrain on the eastern half of the island of Timor in Southeast Asia. East Timor includes the eastern half of Timor, the Ocussi-Ambeno region on the northwest portion of the island of Timor, and the islands of Atauro and Jaco. The country is located northwest of Australia in the Lesser Sunda Islands at the eastern end of the Indonesian Archipelago. 'Timor' is a Portuguese derivation of 'Timor', the Malay word for "Orient"; the island of Timor is part of the Malay Archipelago and is the largest and easternmost of the Lesser Sunda Islands. East Timor is the only Asian nation to lie entirely within the Southern Hemisphere. The Loes River is the longest with a length of 80 km (50 mi). This river system covers an area of 2,184 km2 (843 sq mi). It is a small country with a land size of 14,919 km2 (5,760 sq mi). The exclusive economic zone is 70,326 km2 (27,153 sq mi).

<span class="mw-page-title-main">Economy of East Timor</span>

The economy of East Timor is a low-income economy as ranked by the World Bank. It is placed 133rd on the Human Development Index, indicating a medium level of human development. 20% of the population is unemployed, and 52.9% live on less than $1.25 a day. About half of the population is illiterate. At 27%, East Timor's urbanisation rate is one of the lowest in the world.

<span class="mw-page-title-main">Banda Sea</span> A sea between Sulawesi and Maluku

The Banda Sea is one of four seas that surround the Maluku Islands of Indonesia, connected to the Pacific Ocean, but surrounded by hundreds of islands, including Timor, as well as the Halmahera and Ceram Seas. It is about 1000 km (600 mi) east to west, and about 500 km (300 mi) north to south.

<span class="mw-page-title-main">Santos Limited</span> Australian energy company

Santos Ltd. is an Australian oil and gas exploration and production company, with its headquarters in Adelaide, South Australia. It owns liquefied natural gas (LNG), pipeline gas, and oil assets. It is the biggest supplier of natural gas in Australia, with its plants in the Cooper Basin in South Australia and South West Queensland supplying the eastern states of Australia. Its operations also extend to the seas off Western Australia and Northern Territory.

Woodside Energy Group Ltd is an Australian petroleum exploration and production company. Woodside is the operator of oil and gas production in Australia and also Australia's largest independent dedicated oil and gas company. It is a public company listed on the Australian Securities Exchange and has its headquarters in Perth, Western Australia. In the 2020 Forbes Global 2000, Woodside was ranked as the 1328th-largest public company in the world.

<span class="mw-page-title-main">Timor Gap</span> Area of the Timor Sea between Australia and Timor Island

The Timor Gap is an area of the Timor Sea between Australia and Timor Island. The island is divided between independent East Timor and West Timor province of Indonesia.

<span class="mw-page-title-main">Timor Gap Treaty</span>

The Timor Gap Treaty was formally known as the Treaty between Australia and the Republic of Indonesia on the zone of cooperation in an area between the Indonesian province of East Timor and Northern Australia. It was a bilateral treaty between the governments of Australia and Indonesia, which provided for the joint exploitation of petroleum and hydrocarbon resources in a part of the Timor Sea Seabed. The treaty was signed on 11 December 1989 and came into force on 9 February 1991. The signatories to the treaty were then Australian Foreign Affairs Minister Gareth Evans and then Indonesian Foreign Minister Ali Alatas.

<span class="mw-page-title-main">Inpex</span>

INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore Petroleum Exploration Co., Ltd. INPEX is the largest oil and gas exploration and production company in Japan, with global exploration, development and production projects in 20 countries. In the 2020 Forbes Global 2000, INPEX was ranked as the 597th -largest public company in the world.

<span class="mw-page-title-main">Timor Sea Treaty</span> 2002 geopolitical agreement

Formally known as the Timor Sea Treaty between the Government of East Timor and the Government of Australia was signed between Australia and East Timor in Dili, East Timor on 20 May 2002, the day East Timor attained its independence from United Nations rule, for joint petroleum exploration of the Timor Sea by the two countries. The signatories of the treaty were then Australian prime minister John Howard and his East Timorese counterpart at that time Mari Alkatiri.

<span class="mw-page-title-main">Petroleum industry in Western Australia</span> Overview of WA energy sector

The petroleum industry in Western Australia is the largest contributor to the country's petroleum exports. Western Australia's North West Shelf (NWS) is the primary location from which production originates. Oil exports are shipped from Port Hedland.

<span class="mw-page-title-main">Treaty on Certain Maritime Arrangements in the Timor Sea</span>

Officially called the Treaty between Australia and the Democratic Republic of Timor-Leste on Certain Maritime Arrangements in the Timor Sea (CMATS), the treaty provides for the equal distribution of revenue derived from the disputed Greater Sunrise oil and gas field between Australia and East Timor. The field is located in the Timor Gap where Australia and East Timor have overlapping claims over the continental shelf or seabed. Prior to the treaty, East Timor would only have received about 18% of the revenue from the field.

<span class="mw-page-title-main">Australia–East Timor relations</span> Bilateral relations

Bilateral relations exist between Australia and East Timor. Both countries are near neighbors with close political and trade ties. East Timor, the youngest and one of the poorest countries in Asia, lies about 610 kilometres northwest of the Australian city of Darwin and Australia has played a prominent role in the young republic's history.

<span class="mw-page-title-main">Montara oil spill</span>

The Montara oil spill was an oil and gas leak and subsequent slick that took place in the Montara oil field in the Timor Sea, off the northern coast of Western Australia. It is considered one of Australia's worst oil disasters. The slick was released following a blowout from the Montara wellhead platform on 21 August 2009, and continued leaking until 3 November 2009, when the leak was stopped by pumping mud into the well and the wellbore cemented thus "capping" the blowout. The West Atlas rig is owned by the Norwegian-Bermudan Seadrill, and operated by PTTEP Australasia (PTTEPAA), a subsidiary of PTT Exploration and Production (PTTEP) which is in turn a subsidiary of PTT, the Thai state-owned oil and gas company was operating over on adjacent well on the Montara platform. Houston-based Halliburton was involved in cementing the well. The Montara field is located off the Kimberley coast, 250 km (160 mi) north of Truscott airbase, and 690 km (430 mi) west of Darwin. Sixty-nine workers were safely evacuated from the West Atlas jackup drilling rig when the blowout occurred.

This is a list of notable events relating to the environment in 2009. They relate to environmental law, conservation, environmentalism and environmental issues.

<span class="mw-page-title-main">Australia–East Timor spying scandal</span>

The Australia–East Timor spying scandal began in 2004 when the Australian Secret Intelligence Service (ASIS) clandestinely planted covert listening devices in a room adjacent to the East Timor (Timor-Leste) Prime Minister's Office at Dili, to obtain information in order to ensure Australia held the upper hand in negotiations with East Timor over the rich oil and gas fields in the Timor Gap. Even though the East Timor government was unaware of the espionage operation undertaken by Australia, negotiations were hostile. The first Prime Minister of East Timor, Mari Alkatiri, bluntly accused the Howard government of plundering the oil and gas in the Timor Sea, stating:

"Timor-Leste loses $1 million a day due to Australia's unlawful exploitation of resources in the disputed area. Timor-Leste cannot be deprived of its rights or territory because of a crime."

Peter Cockcroft is an Australian Petroleum geologist, researcher and oil industry executive.

<span class="mw-page-title-main">Amadeus Gas Pipeline</span> Australian natural gas pipeline

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<span class="mw-page-title-main">Bonaparte Basin</span> Sedimentary basin in Western Australia and the Northern Territory

The Bayu-Undan to Darwin Pipeline, also known as the Bayu-Undan Gas Export Pipeline or Gas Export Pipeline (GEP), is a multi-diameter subsea gas export pipeline which transports dry gas from the Bayu-Undan field in the Timor Sea to the Darwin LNG plant at Wickham Point, near Darwin, Northern Territory.


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  12. Darwin LNG
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