Thousands of Aussie travellers excited for a two week cruise around New Zealand have been left gutted after their itinerary was flipped and the ship was rejected by border control.

P&O Cruises Australia told 9News that the 13-day Kiwi Adventure voyage onboard the Pacific Adventure had a change of plans and instead set sail for Tasmania after the ship was turned around in New Zealand waters.

Pacific Adventure left Sydney on Monday and was on its way to the Bay of Plenty, where it was set to get its hull cleaned, when the weather disrupted its journey, a spokesperson has revealed.

“We apologise that the itinerary has had to be amended,” the representative said.

New Zealand’s strict border control stopped the ship from entering the country’s waters because the hull had not been cleaned beforehand.

“A change in the forecast conditions made it too dangerous for divers, and therefore we are unable to gain clearance to enter New Zealand,” the spokesperson said.

Cape Brett Lighthouse, Cape Brett Scenic Reserve in the Bay of Islands, Northland. Photo / Shaun Barnett

This resulted in a major change to the itinerary and a lot of angry passengers.

“In lieu of sailing around New Zealand, Pacific Adventure is on her way to Tasmania, and we hope guests will enjoy their time in Hobart, Port Arthur and Eden,” the spokesperson said.

P&O Cruises Australia also said that travellers were told before embarking on the cruise that there could be “significant changes to the itinerary” due to Aotearoa’s strict biosecurity requirements.

"Guests have been offered additional compensation in light of this change to their itinerary,” the representative said.

Guests on board the cruise ship are fuming at the change, taking to social media to slam the cruise.

“This is just a turd covered in gold glitter. My husband has requested ET bring him home,” one angry traveller wrote.

"Get me off this boat and give me a full refund,” another said.

“I honestly just want to go back home. Take me to Sydney,” another guest shared.