Why the Interislander will be down to one ship for 71 days over the next three months
Tuesday, 7 July 2026
EXPLAINER | If you were to go on the Interislander booking site to look for a Cook Strait sailing for tomorrow you would only be offered the chance to go on one ship, the Kaitaki.
But just over a year ago you may have had the option to travel on three different ferries. So what has happened?
The change stems from the retirement of the Aratere in August last year, which was taken out of service due to it not being able to berth while port upgrades were being done for the new ferries set to arrive in 2029.
Now the Cook Strait service is down to two ships - the 31-year-old Kaitaki and the 28-year-old Kaiārahi - until 2029 when their larger purpose-built replacements arrive.
Given their age it is important the ferries get regular maintenance to avoid any unplanned disruption on the strait. KiwiRail - the company which runs Interislander - does this during winter, the service’s least busy period.
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It does mean that till Monday next week Kaiārahi will be out of service, then from July 18 to September 26 Kaitaki will not be crossing the strait as it gets a dry dock service in Singapore.
That means from today there will be 71 days where the Interislander has only one ship running across Cook Strait.
Transporting NZ chief executive Dom Kalasih said the reduction in ships had been managed well so far but it was still a “risky period”.
Kalasih said there was concern about an Interislander or Bluebridge vessel being forced out of service at short notice, warning that an unplanned outage could leave the sector without enough shipping capacity to move freight.
KiwiRail told The Post with just one ship operating “any outage would be significant”.
“Once services resume, Interislander would prioritise time-critical and essential freight and actively support customers to use alternative options, including other operators and coastal shipping where possible.”
The rail company said that 99% of its sailings had gone ahead as scheduled over the past financial year, reflecting what it described as an “enhanced maintenance regime”.
“The winter maintenance period has been planned and communicated well in advance to our customers and industry partners and this has enabled their own plans to me made through this period.
“KiwiRail has also relaunched its NZ Connect coastal service to support customers who can use coastal shipping during this period.”
The company said it had not considered leasing an additional vessel for the period it would be operating with only one ferry, arguing that doing so was “not practical or economically viable” given due to Cook Strait’s unique operating conditions, regulatory requirements, crewing needs and port compatibility constraints.
It hasn’t always been smooth sailing for the Interislander over the last few years with the Kaitaki losing power in January 2023 and the now-retired Aratere being grounded in 2024.
Following its retirement the Aratere was renamed Vega and was sitting off the coast of Nelson for months while it waited for approval to enter India so it could be scrapped.
The ship made headlines last week when social media footage showed it arriving in India where it will be dismantled.