“My colleague Andy was ahead of me and txt to say you’re in for a surprise. He didn’t elaborate on what it was,” Donaldson told the Herald.

The tour group travelled a little further along the beach until they could see a giant white lump on the beach.

Straight away Donaldson knew what it was, but what was about to unfold left his passengers buzzing with excitement.

He told his tour group they were going to get the chance to see a giant squid up close and personal, something that is a once-in-a-lifetime experience.

“I announced it to the passengers and we all got out to take a look. They were full of excitement.

“For most people it’s a once-in-a-lifetime opportunity, or not even a once-in-a-lifetime.

“It’s not a common find on any beach so if you’re able to be there at the right time, because things that wash up on the beach, organic material doesn’t last on the beach.”

Donaldson and a passenger measured out the giant squid, and estimated the mantle and head were close to 4m in length, not including the tentacles.

The tour guide believes some of the tentacles had been chewed off and thinks it had recently been washed up already dead.

“The tentacles on it were chewed back. It looked like they had been chewed back by some other sea creatures such as small sharks or fish. While I don’t know for sure, I imagine it had been floating out there for a period of time and had washed up.”

While it’s not the first time Farewell Spit Tours has come across a giant squid, Donaldson explained it’s an extremely rare part of nature most people would never see, even if there is an element of sadness to it.

“When it’s something a bit different it’s a special thing to experience. But at the same time there was some sadness about a creature like that. A magnificent example of a large sea creature that lives at the bottom of the ocean unfortunately on the beach not alive anymore.”

Farewell Spit Tours has been running since 1986, with Donaldson explaining they’ve only likely come across about six giant squid in that time, most of those generally between 4 to 6m in length.

He said the Department of Conservation has been contacted, and that giant squid have previously been sought-after by scientists as examples that they can study.

The company’s last sighting of a giant squid was in 2019 when they spotted a five-and-a-half metre-long invertebrate stranded on the sand.

The majority of the giant squid spotted by Farewell Spit Tours have been between 5 to 6m in length.

NIWA said while squid are common, they are seldom seen at the surface and are not very common to spot.

According to AUT Lab for Cephalopod Ecology and Systematics, giant squid can grow up to 13m long and weigh up to 300kg.

They usually live in a depth of about 500m and don’t come to the surface once they are fully grown, making it rare to spot them washed up on shore.

The giant squid is the second-largest mollusc and one of the largest of all extant invertebrates. It is only exceeded by the colossal squid.

The two species (giant squid and colossal squid) are from different families and the colossal is only found in Antarctic waters.

NIWA told the Herald the biggest giant squid measured in New Zealand waters was 13m long.

They said colossal squids have shorter tentacles and much heavier bodies. The colossal squid has the largest beak of any cephalopod.

AUT squid scientists have examined just over 50 giant squid in the past 20 years.

They are usually caught accidentally in commercial fishing or research trawls, or are washed up on beaches.