Can you swim between New Zealand islands?

A Scot has set a new world record for the fastest swim across the Cook Strait - the waters between New Zealand's North and South Islands. Andy Donaldson, 31, swam through the night to complete the 23km route in four hours and 33 minutes.



Swimming between New Zealand's North and South Islands across the Cook Strait is possible but is considered one of the most dangerous and difficult marathon swims in the world. The straight-line distance is approximately 22 kilometers (14 miles) at its narrowest point, but the powerful and unpredictable "washing machine" currents mean swimmers often cover much more ground. In 2026, fewer than 150 people have successfully completed the crossing. The water temperature is typically a chilly 14°C to 19°C (57°F to 66°F), and the strait is famous for its extreme tides and frequent shark sightings. Anyone attempting this must have a dedicated support boat, a qualified pilot, and significant open-water experience. For the average person, "swimming between the islands" is not a recreational activity; instead, visitors take the Interislander or Bluebridge ferry, which provides a scenic three-hour journey across the strait, allowing you to appreciate the scale of the water safely from the deck.

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It would be engineeringly impossible to build a bridge or tunnel between the North and South Islands of NZ using current engineering technology. Cook Strait is very deep and the several earthquake fault lines would preclude a tunnel.

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A Scot has set a new world record for the fastest swim across the Cook Strait - the waters between New Zealand's North and South Islands. Andy Donaldson, 31, swam through the night to complete the 23km route in four hours and 33 minutes. It was the third leg of seven comprising the Oceans Seven challenge.

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Cook Strait, strait separating the North and South islands of New Zealand, extending northwest to southeast from the Tasman Sea to the south Pacific Ocean. About 14 miles (23 km) wide at its narrowest point, it averages 420 feet (128 m) in depth.

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How cold is the water in NZ? Being long and skinny, New Zealand's ocean temperatures vary from island to island. The North Island enjoys temperatures of 20-22°C in summer, while in winter, it drops down to 15°C.

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The South Island is very different from the North Island. For starters it's larger than the North Island and generally considered more beautiful. It also has gorgeous coastline, though it's best known for the many mountains and fjords that define its inland.

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Generally speaking, if you want to engage with city culture or explore Maori history, the North Island is for you. If you want to deep-dive into nature, the South Island has plenty of lakes, mountains, fjords, and glaciers to discover.

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New Zealand's most famous and beautiful ferry route is between Wellington in the North Island and Picton in the South Island. The journey between the two islands is commonly referred to as 'crossing the Cook Strait'. The sailing time is around 3.5 hours (weather dependent).

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Cook Strait can also be one of the world's roughest stretches of water. It's part of the westerly wind belt known as the Roaring Forties. As the only gap between the mountainous main islands of the country, the strait acts like a huge wind tunnel.

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