Cook Strait
One of the most dangerous and unpredictable waters in the world
Cook Strait separates New Zealand’s North and South Islands, linking the Tasman Sea to the northwest with the South Pacific Ocean to the southeast. At its narrowest point, it measures 22 km across, and it is often called “one of the most dangerous and unpredictable waters in the world.” Regular ferries travel the route between Wellington and Picton in the Marlborough Sounds.
The strait is named for James Cook, the first European commander to sail through it, in 1770. Its waters are shaped by powerful tidal flows, and the tides are unusual: high water at one end of the strait coincides with low water at the other. Many ships have been wrecked here with heavy loss of life, including the *Maria* (1851), the *City of Dunedin* (1865), the *St Vincent* (1869), the *Lastingham* (1884), and others in 1909 and 1968.
In Māori legend, the navigator Kupe discovered the strait while pursuing a monstrous octopus, Te Wheke-a-Muturangi, across it in his canoe, finally destroying it in Tory Channel or at Pātea. When Dutch explorer Abel Tasman first saw New Zealand in 1642, he thought the strait was a closed bight and named it Zeehaen’s Bight after his ship, the *Zeehaen*. James Cook proved it was a navigable strait in 1769.
European settlers arrived in the early 19th century. Whalers set up bases in the Marlborough Sounds—at Tory Channel and Port Underwood—and in the Kāpiti area, drawn by whale migration routes. From the late 1820s until the mid-1960s, Arapaoa Island served as a whaling base; Perano Head on its east coast became the main whaling station from 1911. The Perano family’s houses now operate as tourist accommodation.
During the 1820s, Te Rauparaha led a Māori migration to the Cook Strait region, with Ngāti Toa arriving in 1822. From 1840, permanent settlements appeared—first at Wellington, then at Nelson and Whanganui (then called Petre). Early settlers viewed the strait more broadly than today, stretching from Taranaki to Cape Campbell, and these towns clustered around it as the colony’s central waterway.
Between 1888 and 1912, a Risso’s dolphin named Pelorus Jack became famous for escorting ships through Cook Strait, usually seen in Admiralty Bay near French Pass. He survived a failed assassination attempt and was protected by a 1904 New Zealand law. During periods of invasion fear, coastal fortifications were built. In World War II, two 23 cm gun installations on Wrights Hill behind Wellington could fire 28 km across the strait, and thirteen 15 cm guns were placed around Wellington, the Mākara coast, and the Marlborough Sounds entrances. Many remains still exist.
Pencarrow Head Lighthouse, at the strait’s entrance to Wellington Harbour, was New Zealand’s first permanent lighthouse. Its first keeper, Mary Jane Bennett, was the country’s only female lighthouse keeper. It was decommissioned in 1935 and replaced by Baring Head Lighthouse.
About 18,000 years ago, during the Last Glacial Maximum, sea levels were over 100 m lower. Cook Strait was then a deep harbour of the Pacific Ocean, cut off from the Tasman Sea by coastal plains connecting the North and South islands. Sea levels rose 7,000 years ago, separating the islands and linking the strait to the Tasman Sea.
The strait runs northwest to southeast, with the South Island on the west and the North Island on the east. At its narrowest, 22 km separate Cape Terawhiti (North Island) from Perano Head on Arapaoa Island (South Island)—though Perano Head lies further north. In clear weather, the opposite shore is visible. The west coast runs 30 km along Cloudy Bay and past the Marlborough Sounds; the east coast runs 40 km along Palliser Bay, past Wellington Harbour, suburbs, and another 15 km to Mākara Beach.
The Brothers, a tiny island group off Arapaoa Island’s east coast, include North Brother, a sanctuary for the rare Brothers Island tuatara, and the largest island, site of the Brothers Island Lighthouse. The strait’s shores are mostly steep cliffs. Beaches at Cloudy Bay, Clifford Bay, and Palliser Bay slope gently to 140 m, where a submarine plateau lies. The bottom topography is complex: to the east lies the Cook Strait Canyon, descending into the Hikurangi Trough; to the northwest is the Narrows Basin, 300 to 400 m deep. Fisherman’s Rock sits at the north end.
Quick Facts
- Other Name
- Te Moana-o-Raukawa (Māori)
- Countries
- New Zealand
- Min Width
- 22 km
- Depth
- 128 m
- Temperature High
- 17.8 C (north-western approach summer average)
- Temperature Low
- 9.4 C (south-eastern approach winter average)
- Frozen
- No
Facts from the source article.
Lore & Background
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. 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. The strait is named after James Cook, the first European commander to sail through it, in 1770. 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, based out of Tory Channel and Port Underwood, and also in the Kāpiti area. From the late 1820s until the mid-1960s Arapaoa 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 from 1911. During the 1820s Te Rauparaha led a Māori migration to, and the conquest and settlement of, the Cook Strait region. In 1822 Ngāti Toa migrated to Cook Strait region, led by Te Rauparaha. From 1840 more permanent settlements sprang up, first at Wellington, then at Nelson and at Whanganui (Petre). Between 1888 and 1912 a Risso's dolphin named Pelorus Jack became famous for meeting and escorting ships around Cook Strait. Pelorus Jack was usually spotted in Admiralty Bay between Cape Francis and Collinet Point, near French Pass. 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 23 cm gun installations were constructed on Wrights Hill behind Wellington. These guns could range 28 km across Cook Strait. In addition thirteen 15 cm gun installations were constructed around Wellington, along the Mākara coast, and at entrances to the Marlborough Sounds. The Pencarrow Head Lighthouse at the entrance from Cook Strait to Wellington Harbour was the first permanent lighthouse built in New Zealand. Its first keeper, Mary Jane Bennett, was the only female lighthouse keeper in New Zealand's history. The light was decommissioned in 1935 when it was replaced by the Baring Head Lighthouse.
Reader's Guide
Approximately 18,000 years ago during the Last Glacial Maximum when sea levels were over 100 m lower than present day levels, Cook Strait was a deep harbour of the Pacific Ocean, disconnected from the Tasman Sea by the vast coastal plains which formed at the South Taranaki Bight which connected the North and South islands. Sea levels began to rise 7,000 years ago, eventually separating the islands and linking Cook Strait to the Tasman Sea. The strait runs in a general NW-SE direction, with the South Island on the west side and North Island on the east. At its narrowest point, 22 km separate Cape Terawhiti in the North Island from Perano Head on Arapaoa Island in the Marlborough Sounds. The west (South Island) coast runs 30 km along Cloudy Bay and past the islands and entrances to the Marlborough Sounds. The east (North Island) coast runs 40 km along Palliser Bay, crosses the entrance to Wellington Harbour, past some Wellington suburbs and continues another 15 km to Mākara Beach. The Brothers is a group of tiny islands in Cook Strait off the east coast of Arapaoa Island. North Brother island is a sanctuary for the rare Brothers Island tuatara, while the largest of the islands is the site of the Brothers Island Lighthouse. 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 m. To the east is the Cook Strait Canyon with steep walls descending eastwards into the bathyal depths of the Hikurangi Trough. To the north-west lies the Narrows Basin, where water is 300 and 400 m deep. Fisherman's Rock in the north end of the Narrows Basin rises to within a few metres of low tide. The strait has an average depth of 128 m. In 1855 a severe earthquake occurred on both sides of Cook Strait. In 2013 two large earthquakes measuring 6.5 and 6.6 on the Richter Scale struck Cook Strait, causing significant damage in the town of Seddon, with minor to moderate damage in Wellington. The waters of Cook Strait are dominated by strong tidal flows. The tidal flow through Cook Strait is unusual in that the tidal elevation at the ends of the strait are almost exactly out of phase with one another, so high water on one side meets low water on the other. On the Pacific Ocean side the high tide occurs five hours before it occurs at the Tasman Sea side.
Did You Know?
- A number of ships have been wrecked in Cook Strait 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, in 1909 and in 1968.
- Pelorus Jack, a Risso's dolphin, became famous between 1888 and 1912 for meeting and escorting ships around Cook Strait.
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