| Tasman Sea "The Ditch" | |
| Image Bathymetry: | Tasman Sea.jpg |
| Alt Bathymetry: | Map of the Tasman Sea |
| Caption Bathymetry: | Map of the Tasman Sea |
| Location: | Western Pacific Ocean |
| Type: | Sea |
| Basin Countries: | Australia, New Zealand |
| Length: | 2800km (1,700miles) |
| Width: | 2200km (1,400miles) |
| Area: | 2300000km2 |
| Islands: | Lord Howe Island, Norfolk Island |
| Benches: | Lord Howe Rise |
| Cities: | Newcastle, Sydney, Wollongong, Hobart (Australia) Auckland, Wellington, New Plymouth, Whanganui (New Zealand) |
The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about 2000km (1,000miles) across and about 2800km (1,700miles) 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.[1]
The Tasman Sea is informally referred to in both Australian and New Zealand English as the Ditch; for example, "crossing the Ditch" means travelling to Australia from New Zealand, or vice versa. The diminutive term "the Ditch" used for the Tasman Sea is comparable to referring to the North Atlantic Ocean as "the Pond".
The south of the sea is passed over by depressions going from west to east. The northern limit of these westerly winds is near to 40°S. During the southern winter, from April to October, the northern branch of these winds from the west changes its direction toward the north and goes up against trade winds. Hence, the sea receives frequent winds from the southwest during this period. In the Australian summer (from November to March), the southern branch of the trade winds goes up against west winds and produces further wind activity in the area.
The Tasman Sea is 2250km (1,400miles) wide and has an area of 2300000km2.[1] The maximum depth of the sea is 5943m (19,498feet).[2] 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 International Hydrographic Organization defines the limits of the Tasman Sea as:[3]
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.[4]
The Tasman Sea features a number of midsea island groups, quite apart from coastal islands located near the Australian and New Zealand mainlands:
The East Australian Current that commences its flow southwards in the tropics of the Coral Sea, near the eastern coast of Australia is the most energetic circulation feature in the south western Pacific Ocean and is a primary means of heat transport from the tropics to the middle latitudes between Australia and New Zealand.[9] The East Australian Current is a return of the westward-flowing Pacific Equatorial Current (Pacific South Equatorial Current).[10] At the juncture between the Tasman and Coral seas while the East Australian Current continues south in the western Tasman a branch flows east called the Tasman Front towards the north of New Zealand with most continuing eastward above New Zealand into the South Pacific Ocean. It transpires that while predominantly the location of westerly wind stress is a factor in how far north the formation of the Tasman Front occurs, so is the presence of the New Zealand land mass, as the top of New Zealand defines the furtherest south that the Tasman Front can be split off by the westerly winds. A boundary current called the East Auckland Current goes down the west coast of the North Island and further south the East Cape Current, that has been diverted towards the South Island by the shapes of the Lord Howe Rise and southern east coast of the North island continues to the south. The East Australian Current south of Tasmania also is diverted west in the Subtropical Front which collides with the western moving Subantarctic front of the Antarctic Circumpolar Current. The East Australian Current sheds eddies on its way south that move south-westward with some known as the Tasman Leakage making it as far westward as the Indian Ocean.
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.[11]
In 1876, the first telegraph cable connecting Australia and New Zealand was laid in the Tasman Sea.[12] The telegraph cable was made obsolete in 1963 when the Commonwealth Pacific Cable, New Zealand's first international telephone cable, was completed.[13] 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.[14]