With the help of Ros and Gordon Butt, Cat Balou's very experienced operators, the passengers were treated to the amazing site of a large pod of killer whales, or orcas.

What they didn't know at the time was that they had recorded images of a type of killer whale never before seen in Australian waters.

The marine centre asked David Donnelly, marine wildlife consultant and a frequent visitor to this region to research whales and dolphins, to study the images.

Dave immediately recognised that they were not the animals he has spent years recording.

He has confirmed that the killer whales seen off Eden at Easter are "Type C Antarctic Killer Whales".

"This news is extremely exciting and adds to the growing interest in this region as a study area for cetacea, as this is the very first record of the Antarctic killer whale appearing in Australian waters," marine centre coordinator Jenny Robb said.

"It is also only the second time that this species of orca has been seen outside Antarctica."

Mr Donnelly said the Antarctic killer whale is distinguishable by the angled sweeping eye patch and the pronounced saddle and cape on their backs.

He said he had been bombarded with calls from international researchers after they had seen the photographs.

"Not only is this the first time they have been seen in Australia, it is only the second time that they have been recorded outside Antarctica," Ms Robb said.

"It is very unusual, almost unique, to find animals that are usually in ice mixing with tropical species.

"It proves again that ocean off Eden is just such an exciting area to study marine bio-diversity where the cold southern currents meet with the warm currents from the north."

Ms Robb said the area continued to attract researchers from across the world and the marine centre was keen to encourage more of this activity.

"If any locals spot something they think is unusual or interesting, they are urged to make contact with the our office. We can then link up with our extensive network of marine researchers to see what else we can learn about the unique marine environment we enjoy here."