A scuba diving instructor from Byron Bay is being labelled 'a hero' for risking his life to save a distressed grey nurse shark in a marine park off northern New South Wales.

Inaki Aizpun received the Hero to Animals Award from the activist group PETA for removing a discarded fishing net from between the jaws of the two-metre shark a few weeks ago.

Mr Aizpun was taking a group of people scuba-diving off Julian Rocks when he noticed the distressed shark.

On closer inspection, he saw a rope and net caught in the grey nurse's mouth.

Mr Aizpun said he had to swim very close to the shark to see if there was hook attached to the rope and net.

"Luckily, there wasn't a hook so I could start pulling on the rope and net," he said.

"The shark was also moving to try to discard the material from its mouth."

Byron Bay scuba diver Inaki Aizpun, who removed net from the mouth of a grey nurse shark. ( Supplied: Inaki Aizpun )

The plucky scuba diver was very close to the grey nurse shark but felt it understood that he was trying to help and therefore, did not attack him.

"I think the shark knew that I was there for a good cause," Mr Aizpun said.

"That I was there to help him because it didn't at anytime come towards me or act aggressively.

"The shark knew that it was going to die so it cooperated with me and after a while, I just managed to get it out."

Mr Aizpun said the grey nurse shark briefly disappeared from his sight but returned to face him.

"I could see in the shark's eyes that it was thanking me for saving its life and then it swam away," he said.

He was surprised at the large amount of fishing net that had been lodged in the shark's mouth.

The scuba diver admitted that sadly, he had seen more and more marine life entangled in discarded fishing nets or wounded by fish hooks.

PETA spokesperson, Emily Rice, said they had given Mr Aizpun an award to thank him for his quick action and compassion in saving the shark.

"We hope he inspires others to come to the aid of an animal in need," she said.