A marine conservationist near the Hawaiian island of Oahu has captured stunning photographs of her close encounter with a huge great white shark — and landed in hot water with other researchers as a result.

Key points: Ocean Ramsey says she put her hand out to maintain a small gap as the shark passed

Ocean Ramsey says she put her hand out to maintain a small gap as the shark passed Video from a different moment shows her swimming beside a shark and touching it twice

Video from a different moment shows her swimming beside a shark and touching it twice Some researchers say it is a bad practice to touch marine life and filming it could encourage more people to do the same

Divers came across the massive animal when the carcass of a dead sperm whale drew it and a number of other sharks to Oahu's south shore.

Conservationist Ocean Ramsey swam beside the shark and placed her hand on its back.

She suggested the shark could be the famed Deep Blue — one of the largest great white sharks ever recorded — due to its size and markings, but shark researcher Michael Domeier said it was actually a newly-discovered shark named Haole Girl.

Conservationist Ocean Ramsey reaches out to the massive shark off Oahu. ( Instagram: Ocean Ramsey )

Delighted by the "magic" encounter, Ms Ramsey took to Instagram to document her experience.

"I waited quietly, patiently, observing as she swam up to the dead sperm whale carcass and then slowly to me passing close enough I gently put my hand out to maintain a small space so her girth could pass," she said.

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But Dr Domeier used posts on Instagram to criticise Ms Ramsey for touching the animal and posing for photos, saying it could be damaging for the shark, which might be pregnant, and also send the wrong message to other divers.

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"The number 1 rule of legitimate shark diving operators is DON'T TOUCH THE SHARKS! This is not shark advocacy … it is selfish, self-promotion," he said.

Dr Domeier said these sharks spend almost their entire 18-month gestation period in deep offshore waters where food is "very, very scarce".

"Harassing a pregnant white shark while she is trying to feed could cause her to leave the meal … impacting her ability to successfully carry her pups to term or reproduce the next cycle.

"Did you know that the very next day after all the videos went viral there were about 60 people floundering around that dead whale in hopes of having their encounter with a white shark?

"Guess how many sharks were observed: ZERO! Don't you think all those people in the water might intimidate the sharks?

"And if they try to come in and feed they have people climbing all over them, all wanting to be like O. Ramsey? Think about that."

Mr Domeier said the actions sent a dangerous message even though the shark in this instance had recently been feeding and was unlikely to bite.

Aloha Scuba Diving Company posted footage of the encounter that showed Ms Ramsey twice swimming beside the shark and resting her hand on it, while many other scuba divers swam nearby.

The company defended Ms Ramsey as "a highly qualified shark advocate" who "has studied them for years".

On Instagram, Ms Ramsey said she knew some people would criticise her, "but what some don't realise is that sometimes sharks seek touch".

"She swam away escorted by two rough-toothed dolphins who danced around her over to one of my @oneoceandiving shark research vessels and proceeded to use it as a scratching post, passing up feeding for another need.

"I wish more people would have a connection with sharks and the natural world, because then they would understand that it's not petting sharks or pushing them off to maintain a respectable space that is hurting sharks … it's the wasteful and cruel practice of grabbing and catching sharks to cut off their fins."

The home page for Ms Ramsey shows a looping video in which the marine conservationist, free diver and model reaches out and touches two sharks.