Cook Strait is the strait between the North and South Islands of New Zealand. It connects the Tasman Sea on the west with the South Pacific Ocean on the east.

To the south the coast runs runs along Cloudy Bay and past the islands and entrances to the Marlborough Sounds. To the north the coast runs along Palliser Bay, crosses the entrance to Wellington harbour, past some Wellington suburbs and continues another to Makara beach.

The strait is named after James Cook, the first European commander to sail through it, in 1770. In Māori it has the name Raukawa or Raukawa Moana. Raukawa may mean "bitter leaves".

Cook Strait is one of the most dangerous and unpredictable waters in the world. In good weather one can see clearly across the strait. At its narrowest point separate Cape Terawhiti in the North Island from Perano Head on Arapawa Island in the Marlborough Sounds. Counter-intuitively, at this point the South Island coast lies further north than that of the North Island.

History

In Māori legend, Cook Strait was discovered by Kupe the navigator. Kupe followed in his canoe a monstrous octopus called Te Wheke-a-Muturangi across Cook Strait and destroyed it in Tory Channel or at Pātea.

See also: The legend of Whanganui-a-Tara.

When Dutch explorer Abel Tasman first saw New Zealand in 1642, he thought Cook Strait was a bight closed to the east. He named it Zeehaen's Bight, after the Zeehaen, one of the two ships in his expedition. In 1769 James Cook established that it was a strait, which formed a navigable waterway.

Cook Strait attracted European settlers in the early 19th century. Because of its use as a whale migration route, whalers established bases in the Marlborough Sounds and in the Kapiti area. From the late 1820s until the mid 1960s Arapawa Island was a base for whaling in the Sounds. Perano Head on the east coast of the island was the principal whaling station for the area. The houses built by the Perano family are now operated as tourist accommodation.

During the 1820s Te Rauparaha lead a Māori migration to, and the conquest and settlement of, the Cook Strait region.

From 1840 more permanent settlements sprang up, first at Wellington, then at Nelson and at Wanganui (Petre). At this period the settlers saw Cook Strait in a broader sense than today's ferry-oriented New Zealanders: for them the strait stretched from Taranaki to Cape Campbell, so these early towns all clustered around "Cook Strait" (or "Cook's Strait", in the pre-Geographic Board usage of the times) as the central feature and central waterway of the new colony.

Between 1888 and 1912 a dolphin named Pelorus Jack became famous for meeting and escorting ships around the Cook Strait. Pelorus Jack was usually spotted in Admiralty Bay between Cape Francis and Collinet Point, near French Pass, a channel used by ships travelling between Wellington and Nelson. Pelorus Jack is also remembered after he was the subject of a failed assassination attempt. He was later protected by a 1904 New Zealand law.

At times when New Zealand feared invasion, various coastal fortifications were constructed to defend Cook Strait. During the second world war, two 9.2 inch (23 cm) gun installations were constructed on Wrights Hill behind Wellington. These gun could range across Cook Strait. In addition thirteen 6-inch (15 cm) gun installations were constructed around Wellington, along the Makara coast, and at entrances to the Marlborough Sounds. The remains of most of these fortifications can still be seen.

The Pencarrow Head Lighthouse was the first permanent lighthouse built in New Zealand. Its first keeper, Mary Jane Bennett, was the first and only female lighthouse keeper in New Zealand. The light was decommissioned in 1935 when it was replaced by the Baring Head Lighthouse.

A number of ships have been wrecked with significant loss of life, such as the Maria in 1851, the City of Dunedin in 1865, the St Vincent in 1869, the Lastingham in 1884, the SS Penguin in 1909 and the Wahine in 1968.

Geology

The shores of Cook Strait on both sides are mostly composed of steep cliffs. The beaches of Cloudy Bay, Clifford Bay, and Palliser Bay shoal gently down to 140 metres, where there is a more or less extensive submarine plateau. The rest of the bottom topography is complex. To the east is the Cook Strait Canyon with steep walls descending eastwards into the bathyal depths of the Hikurangi Trench. To the north-west lies the Narrows Basin, where water is 300 and 400 metres deep. Fisherman's Rock in the north end of the Narrows Basin rises to within a few metres of low tide, and is marked by waves breaking in rough weather. A relatively shallow submarine valley lies across the northern end of the Marlborough Sounds. The bottom topography is particularly irregular around the coast of the South Island where the presence of islands, underwater rocks, and the entrances to the sounds, create violent eddies. The strait has an average depth of 128 metres (420 feet).

The South and North Islands were joined during the last ice age.

Islands

The Brothers is a group of tiny islands in Cook Strait off the east coast of Arapawa Island. North Brother island in this small chain is a sanctuary for the rare Brothers Island tuatara, while the largest of the islands is the site of the Brothers Island Lighthouse.

Tidal flow

The tidal flow through Cook Strait is unusual. On each side of the strait the tide is almost exactly out of phase, so high water on one side meets low water on the other. Strong currents result, with almost zero tidal height change in the centre of the strait. Although the tidal surge should flow in one direction for six hours and then the reverse direction for six hours, a particular surge might last eight or ten hours with the reverse surge enfeebled. In especially boisterous weather conditions the reverse surge can be negated, and the flow can remain in the same direction through three surge periods and longer. This is indicated on marine charts for the region.

There are numerous computer model representations of the tidal flow through Cook Strait. While the tidal components are readily realizable, the residual flow is more difficult to model.

Tidal power

In April 2008, a resource consent was granted to Neptune Power for the installation of a $10 million experimental underwater tidal stream turbine capable of producing one megawatt. The turbine has been designed in Britain, and will be built in New Zealand. It will be 14 metres in diameter and constructed of carbon fibre. It will be placed in eighty metres of water, 4.5 kilometres due south of Sinclair Head, in waters known as the “Karori rip”. Power from the turbine will be brought ashore at Vector's Island Bay substation. The turbine is a pilot, and will be sited in slower tides for testing. Neptune hopes to generate power from the unit by 2010. The company claims there is enough tidal movement in Cook Strait to generate 12 GW of power, more than one-and-a-half times New Zealand's current requirements. In practice, only some of this energy could be harnessed.

On the other side of the strait, Energy Pacifica has applied for resource consent to install up to 10 marine turbines, each able to produce up to 1.2 MW, near the the Cook Strait entrance to Tory Channel. They claim Tory Channel is an optimal site with a tidal current speed of 3.6 metres a second and the best combination of bathymetry and accessibility to the electricity network.

The power generated by tidal marine turbines varies as the cube of the tidal speed. Because the tidal speed doubles, eight times more tidal power is produced during spring tides than at neaps.

Cables

Electric-power and communication cables link the North and South Islands across Cook Strait. These cables are currently operated by Transpower.

• Power cables: A high-voltage direct current (HVDC) system uses three undersea cables. During dry periods, this gives the South Island access to gas and coal power generated in the North Island. Likewise, during peak winter periods, it gives the North Island access to power from the large hydroelectric installations in the South Island. The submarine cables are laid on the seabed within a legally defined zone called the cable protection zone (CPZ). The CPZ is about seven kilometres wide for most of its length. It narrows where the cables enter the water at Fighting Bay on the South Island and at Oteranga Bay, Cape Terawhiti, in the North Island. Fishing activities and anchoring boats are prohibited within the CPZ. Transpower has a current proposal to spend nearly $700 million upgrading the electricity link. If implemented, this will have a capacity of 1200 MW by 2014.

• Communication cables: Fibre optic cables carry telecommunications across Cook Strait, used by New Zealand’s main telecommunication companies for domestic and commercial traffic and by Transpower for control of the HVDC link.

Marine life

Giant squid specimens have been washed ashore on Cook Strait or found in the stomachs of sperm whales off Kaikoura.

A colony of male fur seals has long been established near Red Rocks on the Makara Coast, west of Wellington.

Cook Strait offers important habitats to many cetacean species. Several dolphins (Bottlenose,Common, Dusky) frequent in the area along with Killer Whales and the endemic Hector's Dolphins. Long-Finned Pilot Whales often strand in mass at Golden Bay. The famous Pelorus Jack was a Risso's Dolphin being observed escorting the ships between 1888 and 1912, though this species is not a common visitor to the New Zealand's waters.

Migratory large whales attracted many whalers to the area in the winter. Currently, annual survey of counting Humpback Whales is taken by Department of Conservation and former whalers help DOC to spot animals. Other occasional visitors include Southern Right Whales, Blue Whales, Sei Whales and Sperm Whales.

Game fishing

Cook Strait offers good game fishing. Albacore tuna can be caught from January to May. Broadbill swordfish, bluenose, mako sharks and the occasional marlin and white shark can also be caught.

Transport

Ferry

Regular ferry services run between Picton in the Sounds and Wellington. Although Cook Strait is only 24 kilometres wide at its narrowest point, the ferry journey covers 70 kilometres. The strait often experiences rough water and heavy swells from strong winds, especially from the south. New Zealand's position directly athwart the roaring forties means that the strait funnels westerly winds and deflects them into northerlies. Due to this the Cook Strait is regarded as one of the most dangerous and unpredictable waters in the world.

Air

Swimming

According to Māori oral tradition, the first woman to swim Cook Strait was Hine Poupou. She swam from Kapiti Island to Dürville Island with the help of a dolphin. Other Māori accounts tell of at least one swimmer who conquered the strait in 1831.

In modern times, the strait was first swum by Barrie Devenport in 1962. Lynne Cox was the first woman to swim it, in 1975. The most prolific swimmer of the strait is Philip Rush, who has crossed eight times, including two double crossings. Aditya Raut was the youngest swimmer at 11 years. Stephanie Bennington was the youngest female swimmer at 13 years. Pam Dickson was the oldest swimmer at 55 years. By 2008, 71 single crossing had been made by 61 individuals, and three double crossings had been made by two individuals. Crossing times are largely determined by the strong and sometimes unpredictable currents that operate in the strait.

Timeline

• Mists of time: The mythical navigator Kupe follows, in his canoe, the octopus Te Wheke-a-Muturangi across Cook Strait.
• 1642: Abel Tasman mistakes Cook Strait for a bight.
• 1769: James Cook establishes it is a strait
• 1822: Ngati Toa migrates to Cook Strait region, led by Te Rauparaha.
• 1831: Whaling station established in Tory Channel.
• 1851: Maria wrecked in on rocks at Cape Terawhiti, 26 people die.
• 1855: Severe earthquake on both sides of Cook Strait.
• 1865: Paddle steamer City of Dunedin sinks in Cook Strait, 39 people die.
• 1866: Cook Strait submarine telegraph cable laid.
• 1869: St Vincent wrecked in Palliser Bay, 20 people die.
• 1879: Kangaroo lays the first Telegraph cable across Cook Strait.
• 1884: Lastingham wrecked at Cape Jackson, 18 people die.
• 1904: Pelorus Jack is protected by New Zealand law
• 1909: SS Penguin wrecked in Cook Strait, 75 people die.
• 1920: First aeroplane flight across Cook Strait.
• 1935: Air services begin across Cook Strait.
• 1962: Cook Strait rail ferry service begins.
• 1962: Barrie Devenport swims the strait.
• 1964: Cook Strait power cables laid.
• 1968: TEV Wahine wrecked at entrance to Wellington harbour, 53 people die.
• 1975: Lynne Cox is the first woman to swim the strait.
• 1979: Paul Caffyn crosses the strait in a sea kayak.
• 1984: Rush Philip swims the strait both ways.
• 1991: Five new power and communication cables laid
• 1994: First fast-ferry service begins operation across Cook Strait.
• 2002: Two further communications cables laid.
• 2005: The retired frigate HMNZS Wellington is sunk off Wellington as an artificial reef.
• 2008: A resource consent is granted to Neptune Power to install a $10 million experimental underwater tidal stream turbine capable of producing one megawatt.
• 2008: Energy Pacifica applies for resource consent to install up to 10 marine turbines, each able to produce up to 1.2 MW, near the the Cook Strait entrance to Tory Channel.

See also

• Aotearoa Wave and Tidal Energy Association

Notes

References

• Grady, Don (1982) Perano Whalers of Cook Strait, 1911-1964. Intl Specialized Book Service. ISBN 978-0589013929
• Harris, T.F.W. (1990) Greater Cook Strait DSIR Publishing ISBN 0-477-02580-3

External links

• Cook Strait: Ship Wrecks, Swells and Gales
• New Zealand's Cook Strait Rail Ferries:
• NZ: Chance to turn the tide of power supply EnergyBulletin.net
• Lewis, Keith Submarine cables Te Ara - the Encyclopedia of New Zealand, updated 21-Sep-2007.
• History of Cable Bay Station
• A Powerful link: The Cook Strait Cable
• NZ Documentary Film (2007) Fish & Ships The Island Bay fishing fleet.