Seas and Oceans That Surround Australia: A Deep Dive
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Are you aware of the incredible seas and oceans that surround Australia?
From the Indian Ocean in the West to the Coral Sea in the East, Australia is blessed with an abundance of aquatic beauty.
Not only do these waters provide us with numerous opportunities for exploration and recreation, but they also support vital ecosystems and form part of our cultural heritage.
In this article, I will explore some of these amazing waters, including the Southern Ocean, Timor Sea, Great Australian Bight, Arafura Sea, and the Gulf of Carpentaria.
Discover the amazing diversity of our aquatic environment, from its calm waters to its turbulent depths.
The Oceans of Australia
Australia, being an island continent, is encircled by ocean waters in every state, with the exception of the Northern Territory and the ACT.
The Southern Ocean lies to the south but doesn’t directly border the Australian coast, while the Indian Ocean is situated to the west, and the Pacific Ocean stretches to the east.
Pacific Ocean
The Pacific Ocean is a vast body of salt water that stretches from the 60° S parallel in the south all the way to the Arctic in the north.
It’s situated between Asia and Australia to the west and North and South America to the east.
Among the three major oceans, the Pacific stands out as the largest, covering approximately one-third of the Earth’s surface.
Its area, not including the South China Sea, spans about 62.5 million square miles (161.76 million square km).
This makes it twice the area and over twice the water volume of the Atlantic Ocean, which is the next largest oceanic division.
In fact, the Pacific Ocean’s area is so extensive that it surpasses the total land surface of the entire globe.
It reaches from the Bering Strait to the 60° S latitude, a distance that encompasses more than 120° of latitude or nearly 9,000 miles (around 14,500 km).
Indian Ocean
The Indian Ocean is a body of salt water that makes up approximately one-fifth of the world’s total ocean area.
Among the three major oceans of the world, including the Pacific and Atlantic, it ranks as the smallest, the youngest in geological terms, and the most physically intricate.
Stretching over 6,200 miles (10,000 km) between the southern ends of Africa and Australia, the Indian Ocean, excluding its marginal seas, encompasses an area of around 27,243,000 square miles (70,560,000 square km).
With an average depth of 12,274 feet (3,741 meters), its deepest point resides in the Sunda Deep of the Java Trench off Java’s southern coast (Indonesia), plunging to 24,442 feet (7,450 meters).
The boundaries of the Indian Ocean are defined by Iran, Pakistan, India, and Bangladesh to the north; the Malay Peninsula, Indonesia’s Sunda Islands, and Australia to the east; the Southern Ocean to the south; and Africa and the Arabian Peninsula to the west.
It connects with the Atlantic Ocean in the southwest, just south of Africa’s southern tip, and its eastern and southeastern waters blend with those of the Pacific Ocean.
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, is a body of salt water that constitutes roughly one-sixteenth of the Earth’s total ocean area.
Comprising the sections of the world’s ocean located south of the Pacific, Atlantic, and Indian Oceans, along with their tributary seas, the Southern Ocean surrounds Antarctica below the 60° S latitude.
It’s unique in that it is not interrupted by any other continental landmass.
The Southern Ocean’s narrowest point is the Drake Passage, a strait that spans 600 miles (about 1,000 km) in width, positioned between South America and the tip of the Antarctic Peninsula.
Among the Earth’s oceans, only the Arctic Ocean is smaller in area than the Southern Ocean.
The Seas of Australia
Several seas also border Australia’s coast.
Among the seas of Australia are the Arafura Sea, situated between northern Australia, Papua New Guinea, and Timor, and the Coral Sea, which lies between the northeast coast of Australia, Papua New Guinea, and the Solomon Islands.
Additionally, the Tasman Sea can be found off the southeast coast of Australia, nestled between Australia and New Zealand.
Coral Sea
The Coral Sea is a section of the southwestern Pacific Ocean, located to the east of Australia and New Guinea, west of New Caledonia and the New Hebrides, and south of the Solomon Islands.
Spanning approximately 1,400 miles (2,250 km) from north to south and 1,500 miles from east to west, it covers an area of 1,849,800 square miles (4,791,000 square km).
This sea merges with the Tasman Sea to the south, connects with the Solomon Sea to the north, and extends to the east with the Pacific Ocean.
Through the Torres Strait, it is also linked to the Arafura Sea to the west.
Dominating the seafloor north of latitude 20° S is the Coral Sea Plateau, flanked by the Osprey and Swain reefs to the north and south.
Above the plateau lies the Coral Sea Basin. The region’s depths include the South Solomon Trench at 24,002 feet (7,316 m) and the New Hebrides Trench, reaching 25,134 feet.
The sea’s name pays homage to its abundant coral formations, the most renowned of which is the Great Barrier Reef, stretching 1,200 miles (1,900 km) along the northeastern coast of Australia.
Timor Sea
The Timor Sea, a branch of the Indian Ocean, is positioned southeast of Timor Island in Indonesia and northwest of Australia.
Situated at latitude 10° S, the region is notably influenced by both the southeast trade winds and the monsoon belt, making it a common origin for typhoons.
Stretching about 300 miles (480 km) in width, the Timor Sea encompasses roughly 235,000 square miles (610,000 square km).
It opens to the west into the broader Indian Ocean and to the east into the Arafura Sea, which is part of the Pacific Ocean.
The sea reaches its maximum depth of over 10,800 feet (3,300 meters) in the northern Timor Trough, though more than half of the sea’s area is shallower than 650 feet (200 meters).
A consistent southwesterly surface current known as the Timor Current flows throughout the year, averaging speeds of 0.5–1 mile (0.8–1.6 km) per hour.
Additionally, the Timor Sea is recognized for hosting a significant oil field, adding to its economic importance.
Tasman Sea
The Tasman Sea is a part of the southwestern Pacific Ocean, positioned between the southeastern coast of Australia (including Tasmania) to the west and New Zealand to the east.
It extends roughly 1,400 miles (2,250 km) in width and encompasses an area of around 900,000 square miles (2,300,000 square km).
The Tasman Sea connects with the Coral Sea to the north and leads southwest to the Indian Ocean through the Bass Strait and east to the Pacific through Cook Strait.
Named after the Dutch navigator Abel Tasman, who explored it in 1642, the sea’s Australian and New Zealand coasts were further investigated by British mariner Capt. James Cook and other explorers in the 1770s.
With a maximum depth surpassing 17,000 feet (5,200 meters), the Tasman Sea’s seafloor is marked by the unique Tasman Basin.
The water currents, including the South Equatorial Current, trade wind drift, and the dominant East Australian Current, influence the sea’s climate and circulation.
From July to December, the impact of these currents is minimal, allowing colder southern waters to reach as far north as latitude 32° S.
Lord Howe Island, located at this latitude, marks the southernmost point of modern coral reef development.
In the eastern part of the Tasman Sea, surface currents are guided by a western Pacific stream from January to June and by colder sub-Antarctic waters moving north through Cook Strait from July to December.
These various currents contribute to a generally temperate climate in the southern Tasman Sea and a subtropical climate in the northern regions.
Arafura Sea
The Arafura Sea is a shallow part of the western Pacific Ocean, covering an area of 250,000 square miles (650,000 square km) between Australia’s north coast (specifically the Gulf of Carpentaria) and New Guinea’s south coast.
It joins with the Timor Sea to the west and connects with the Banda and Ceram seas to the northwest.
The Torres Strait links it to the Coral Sea on the east.
Most of this sea rests on the Arafura Shelf, which is a section of the broader Sahul Shelf.
This part of the sea is generally shallow, with depths ranging from 165 to 260 feet (50 to 80 meters), though it deepens on its western edge where coral reefs have developed at nearly 2,000 feet (610 meters).
The Arafura Shelf is thought to have been a low-relief land surface with an arid climate before being submerged by the postglacial sea level rise.
In the northern region of the Arafura Sea, the Aru Islands have formed through localized uplift.
These islands border the Aru Trough, a curved trench reaching a maximum depth of 12,000 feet (3,660 meters).
This trough is part of a series of depressions extending across the Ceram, Arafura, and Timor seas, and continuing west into the Indian Ocean as the Java Trench.
Great Australian Bight
The Great Australian Bight is a broad indentation of the Indian Ocean along Australia’s southern coast.
Defined by the International Hydrographic Bureau, its boundaries stretch from West Cape Howe in Western Australia to South West Cape in Tasmania.
However, more commonly recognized borders are between Cape Pasley, Western Australia, and Cape Carnot, South Australia, covering a distance of 720 miles (1,160 km).
The bight’s head meets the arid Nullarbor Plain and is characterized by an impressively uniform and continuous line of cliffs, ranging from 200 to 400 feet (60 to 120 meters) high.
Within the area between Eucla and Israelite Bay on the Bight’s shores, you’ll find the Nuytsland Reserve and the Cape Arid National Park.
West of Eucla, close to the boundary between Western Australia and South Australia, the ancient cliff line is edged by a sandy coastal plain.
Gulf of Carpentaria
The Gulf of Carpentaria is a shallow, rectangular inlet of the Arafura Sea, which is part of the Pacific Ocean, situated along the northern coast of Australia.
For many years overlooked, the gulf gained international prominence in the late 20th and early 21st centuries due to the exploitation of resources such as bauxite, manganese, and prawns (shrimp).
Spanning an area of 120,000 square miles (310,000 square km) with a maximum depth of 230 feet (70 meters), the gulf stands as a rare modern example of an epicontinental sea, a phenomenon more common in earlier geologic times.
Enclosed by Arnhem Land to the west and the Cape York Peninsula to the east, the Gulf of Carpentaria’s floor forms part of the continental shelf shared by Australia and New Guinea.
A ridge across Torres Strait separates the gulf from the Coral Sea to the east, while another ridge extending north from the Wessel Islands divides it from the Banda Basin of the Arafura Sea.
The gradient of the gulf floor is notably low, with the expansive western plains of Queensland gently sloping into the gulf at a rate of only one foot per mile.
The Ocean Currents of Australia
Within Australia’s neighbouring seas and oceans, four significant ocean currents function prominently.
These include the Indonesian Throughflow, the Leeuwin Current, the Antarctic Circumpolar Current, and the East Australian Current.
The Indonesian Throughflow
The Indonesian Throughflow, as the name indicates, is a network of currents transporting water westward from the Pacific Ocean to the Indian Ocean, navigating through the deep passages and straits of the Indonesian Archipelago.
This is the only location globally where warm, equatorial waters transition from one ocean to another, profoundly influencing the characteristics of the Leeuwin Current with its warm tropical water.
The Leeuwin Current
Originating midway along the Western Australian coast, the Leeuwin Current flows southward, encompassing the base of Western Australia.
It then proceeds eastward across the Great Australian Bight, reaching as far as Tasmania’s west coast, known as the Zeehan Current.
The East Australian Current
Starting near Fraser Island in Queensland, the East Australian Current travels southward along Tasmania’s eastern coast.
During summer, this current strengthens and extends further south, often carrying northern tropical species like tuna and large sea turtles into the Bass Strait.
Known as a Western Boundary current, the East Australian Current is famous for shedding eddies off the Queensland and New South Wales coasts.
The Antarctic Circumpolar Current
Spanning 21,000 km, the Antarctic Circumpolar Current is the world’s longest ocean current, moving perpetually eastward in a loop.
It carries an astonishing 165 million to 182 million cubic meters of water every second from west to east, more than 100 times the flow of all the Earth’s rivers combined.
Extending from the ocean’s surface to its bottom, this current encircles Antarctica.
The Antarctic Circumpolar Current is crucial to Earth’s health, maintaining Antarctica’s cold and frozen state.
As the climate warms, it undergoes changes, forming the main connection between the Indian, Pacific, and Atlantic Oceans.
Created by strong westerly winds across the Southern Ocean and significant temperature differences between the Equator and poles, it also contributes to ocean density variation.
The warm, salty surface waters of the subtropics are lighter than the cold, fresher Antarctic waters, resulting in a sloping effect towards Antarctica in constant density levels.
Together, these four currents shape Australia’s marine environment, impacting global weather patterns, marine life, and even human activities along the coastlines.
FAQs: Seas and Oceans That Surround Australia
What ocean surrounds most of Australia?
The Indian Ocean surrounds the western and southern coasts of Australia, while the Pacific Ocean borders the eastern coast.
Therefore, the Indian Ocean can be said to surround most of Australia.
What ocean surrounds Victoria?
Victoria, a state in Australia, is bordered by the Southern Ocean to the south and the Tasman Sea to the southeast.
What are the 7 seas around Australia?
Australia is surrounded by several significant bodies of water, including the Pacific Ocean, Indian Ocean, Southern Ocean, Tasman Sea, Coral Sea, Timor Sea, and the Arafura Sea.
What oceans meet in Australia?
In Australia, the Indian Ocean, Southern Ocean, and Pacific Ocean converge.
Conclusion: Seas and Oceans That Surround Australia
From the vibrant coral gardens of the Great Barrier Reef to the serene waters of the Southern Ocean, Australia’s seas and oceans are an embodiment of natural wonder and ecological importance.
They contribute not only to the country’s economy but also to global biodiversity and climate regulation.
Conservation and responsible exploration of these marine landscapes assure that future generations will continue to marvel at these natural treasures.
