Kayakers blown away by sight of killer whale pod in the Tauranga Harbour

A huge fin and a moment of panic turned into a once in a lifetime opportunity when a kayaker saw an orca in the Tauranga Harbour.

Cosmo Goode, a keen kayaker, does not usually go for a paddle during winter but with the beautiful weather yesterday, he could not help himself.

He took his friend Jack Gunsen on to the water for his first time and the pair saw a "huge dorsal fin" around 4.50pm.

"I thought, oh god, what is that," he said.

But the initial panic quickly disappeared when they saw it was an orca, what he said looked to be a mother and her calf, along with two others.

The calf looked as though its dorsal fin had been bitten off.

"They actually swam under my kayak, it was pretty surreal," he said.

They watched in awe as the orcas swam around, with Goode suspecting the marine mammals may have been trying to get out of the harbour.

The kayakers' close run-in with orcas. Photo / Supplied

There was another small boat with two men when they were first spotted but a few fishing boats came closer when others could see the whales.

Tucker said no one was doing anything to stress out the whales which peacefully swam around.

Te Aihe Toma and three of his friends were coming back from Matakana Island in their dinghy when they came across the pod of orcas.

Toma said the orcas "came out of nowhere" and caught the whole boat by surprise.

The orcas began circling them and they all just sat and watched in awe, he said.

"It was definitely the best feeling I have ever had out on the water."

He said his favourite was the baby orca, as it made such a tiny noise from it's blowhole.

The Department of Conservation estimates there are about 150-200 orca which travel long distances along New Zealand coasts.

Able to grow to nine metres in length, their diet is varied and includes stingrays, salmon, tuna and other fish species as well as squid, octopus, sea birds and sea turtles.

Orca Wild Adventures owner Mark Tucker said orca were transient animals and had a large territory being such big mammals.

Orca Wild Adventures offers up-close and personal experiences for customers but Tucker said it primarily saw dolphins.

Tucker said the unpredictable nature of orcas meant they could not guarantee seeing them to customers on their tour as they usually only saw them four to five times a year.

"They're incredible animals. They're highly intelligent, extremely powerful ... we'll go out of our way if we hear there are orcas," he said.

"It's always a real treat."

Tucker said the whales enjoyed feeding on the stingray in the harbour and would usually spend about four days in the harbour before moving on.