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The Tasman Sea is a marginal sea of the South
Pacific
Ocean, situated between Australia and
New
Zealand. It measures about 2,000 km (1,200 mi) across and about 2,800 km (1,700 mi) from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 was the first known person to cross it. British explorer Lieutenant
James Cook later extensively
navigated the Tasman Sea in the 1770s during his three voyages of exploration.
The Māori people of New Zealand call this sea Te Moana-a-Rehua meaning 'the sea of Rehua' which clashes with the Pacific waters named Te Tai-o-Whitirea ('the sea of Whitirea')
– after Whitirea, Rehua's lover – at Cape Reinga northernmost tip of North Island. In both Australian and New Zealand English, it is nicknamed the Ditch comparable to the North
Atlantic Ocean nicknamed as "the Pond"; for example, "crossing the Ditch" means travelling to Australia from New Zealand or vice versa.
The Tasman Sea is 2,250 km (1,400 mi) wide and has an area of 2,300,000 km2 (890,000 sq mi). The maximum depth of the sea is 5,943 m (19,498 ft). The base of the sea is made up of globigerina ooze. A small zone of pteropod ooze is found to the south of New Caledonia and to the southern extent of 30°S, siliceous ooze can be found.
The Tasman Sea's midocean ridge developed between 85 and 55 million years ago as Australia and Zealandia broke apart during the breakup of supercontinent Gondwana. It lies roughly midway between the continental margins of Australia and Zealandia. Much of Zealandia is submerged, so the ridge runs much closer to the Australian coast than New Zealand's.
A deep-sea research ship, the RV Tangaroa, explored the sea and found 500 species of
fish and 1300 species of invertebrates. The tooth of a megalodon, an extinct
shark, was also found by researchers.
INTERNATIONAL HYDROGRAPHIC ORGANIZATION LIMITS
The International Hydrographic Organization defines the limits of the Tasman Sea as:
WEST: On the West
A line from Gabo Island (near Cape Howe, 37°30'S) to the northeast point of East Sister Island (148°E), thence along the 148th meridian to Flinders Island; beyond this island a line running to the eastward of the Vansittart Shoals to [Cape] Barren Island, and from Cape Barren (the easternmost point of [Cape] Barren Island) to Eddystone Point (41°S) in Tasmania, thence along the east coast to South East Cape, the southern point of Tasmania.
NORTH: On the North
The parallel of 30°S from the Australian coast eastward as far as a line joining the east extremities of Elizabeth Reef and South East Rock (31°47′S 159°18′E) then to the southward along this line to the South East Rock [an outlier of Lord Howe Island].
On the Northeast From the South East Rock to the north point of Three Kings Islands (34°10′S 172°10′E), thence to North Cape in New Zealand.
EAST: On the East
In Cook Strait. A line joining the south extreme of the foul ground off Cape Palliser (Ngawi) and the Lighthouse on Cape Campbell (Te Karaka).
In Foveaux Strait (46°45'S). A line joining the light on Waipapapa Point [sic] (168°33'E) with East Head (47'02'S) of Stewart Island (Rakiura).
On the Southeast A line running from South West Cape, Stewart Island, through the Snares (48°S, 166°30'E) to North West Cape, Auckland Island (50°30′S 166°10′E), through this island to its southern point.
SOUTH: On the South
A line joining the southern point of Auckland Island (50°55′S 166°0′E) to South East Cape, the southern point of Tasmania.
ISLANDS
The Tasman Sea features a number of midsea island groups, quite apart from coastal islands located near the Australian and New Zealand mainlands:
- Lord Howe Island (part of New South Wales)
- Ball's Pyramid (part of New South Wales)
COMMUNICATIONS
In 1876, the first telegraph cable connecting Australia and New Zealand was laid in the Tasman Sea. The telegraph cable was made obsolete in 1963 when the Commonwealth Pacific Cable, New Zealand's first international
telephone cable, was completed. Moncrieff and Hood were the first to attempt a trans-Tasman crossing by plane in January 1928. The aviators were never seen or heard of again. The first successful flight over the sea was accomplished by Charles Kingsford Smith and Charles Ulm later that year. The first person to row solo across the sea was Colin Quincey in 1977. The next successful solo crossing was completed by his son, Shaun Quincey, in 2010.
TASMAN ABYSSAL PLAIN
The Tasman Abyssal Plain, also known as the Eastern Australian Abyss, is an abyssal plain located off the coast of southeast Australia in the Tasman Sea. Extending from southern Queensland to Tasmania, the large submarine plain is distinguished by its delicately sloping terrain and abundant marine biodiversity. The plain's deep sea floor is notable for its important sedimentary deposits and exceptional geological formations, whereby showcasing the earth's physical history. The plain is also known as the East Australian Basin and Tasman Basin.
A multibeam sonar revealed that the continental slope to the eastern Australian abyss was more convoluted and craggy than expected, with the edge being engraved by multiple canyons, sediment slumps, precipices and many areas of exposed rock. The Tasman abyssal plain is characterized by an average depth between 4,000 m (13,000 ft) and 5,000 m (16,000 ft), with a diverse, though scarcely-explored, ecosystem. There is poor knowledge about the benthic fauna at the lower bathyal to abyssal depths, around 2,000 m (6,600 ft), despite the Tasman plain's large size.
A world-first observation of the largely-unexplored abyssal plain took place in 2017, where it created high quality seafloor mapping of Australia's continental edge from southern Queensland to Tasmania. The majority of abyssal species discovered have extensive geographic and bathymetric distributions. Polychaetes, which are marine worms, were the leading members of the deep-sea macrobenthos in the eastern Australian abyss, and therefore were valuable organisms for zoogeographical studies.
The eastern Australian abyss was formed around 90–52 million years ago during the tectonic breaking of Australian and New Zealand continental masses. A south-north expanding ridge previously existed at the plain's centre. Thereafter, the north–south string of Tasmantid seamounts were formed along the Lord Howe Rise by the Australian plate shifting over a crustal centre from 33.5 to 6.4 million years ago. The current basement depths and the sediment thickness hint a Cretaceous age. Today, the abyssal plain stretches from the Chesterfield and Marion plateaus near Queensland's coastal areas, in the north, (at 24°S), to Tasmania's south (48°S), before heading into the
Southern
Ocean.
The upper continental slope off eastern Australia is largely arched from the shelf break down to 1,500 m (4,900 ft). At mid slope depths, around 3,000 m (9,800 ft), it is more indented, with the higher section occasionally forming an escarpment. Finally, on the lower slope, a series of tread-like rocky racks can be found down to the abyssal plain 4,500 m (14,800 ft) to 5,000 m (16,000 ft). The periphery is repeatedly divided by canyons, some of which begin at shelf depths and depressions due to failing of the incline. The International Ocean Discovery Program had a site located 945 km (587 mi) east of Australia, a site that was on an oceanic crust of Late Cretaceous that was formed 74–83 million years ago. Local seismic reflection data indicate a thick series of sediments, around 800 m (2,600 ft), that are deformed by reverse faults and folds.
Although the basin's average maximum depth is around 5,000 m (16,000 ft), there are several small depressions that are deeper; a maximum depth of 5,943 m (19,498 ft) has been discovered just the northwest of
Sydney. Towards the south of the eastern Australian abyss, the basin is confined by the
Indo-Antarctic Ridge with a depth of less than 3,500 m (11,500 ft), thereby restricting the northern movement of deep
Antarctic waters. The link between the eastern Australian abyss and
the Coral Sea is over a ridge where the depth is generally less than 3,000 m (9,800 ft). The eastern Australian continental shelf is comparatively narrow compared with the rest of the continent, since the shelf breaks just 15 km (9.3 mi) away from the coast, where the beginning of the abyssal plain may be as proximate as 60 km (37 mi) from the coast. Geomorphological features in the eastern margin include plateaus, basins, terraces, holes, and submarine canyons.
Map
of the Tasman Sea
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