A woman who swam side-by-side with a shark, the length of a giraffe in Hawaii had never dived with a great white before her "calming" encounter with the big beast.

The six-metre-long shark, named Deep Blue, was drawn to the warm waters of the north shore of Oahu earlier this week to feast on a dead sperm whale.

Professional shark diver and biologist, Kayleigh Burns, exclusively told 9News that the enormous oceanic predator approached her team's boat and started using it as a scratching post when they went out to monitor which sharks may be drawn to the carcass.

"We were very surprised when the great white shark swam up under our boat," Ms Burns told 9News.

She said her colleague, Ocean Ramsey, was the first to approach the "gentle giant" and she kept a safe distance initially.

Ms Ramsey, who is familiar with Deep Blue, having previously swam with the huge shark on research trips to Guadalupe Island in Mexico, filmed the incredible encounter.

"This was the first great white shark I'd interacted with so I was a little bit nervous," Ms Burns said.

"As soon as my mask hit the water, I was filled with joy. It was actually a very peaceful, calming experience."

Ms Burns wants people who have seen the breathtaking footage of her frolicking in the water alongside Deep Blue to see a less aggressive side of sharks, which often only make headlines during attacks.

"She was very graceful, very slow because of her size - As Ocean likes to call her a 'grandma shark'", Ms Burns said.

She said Deep Blue was docile and could differentiate between food and humans.

The group went out at sunrise and Deep Blue stayed with their boat for the majority of the day.

Ms Burns said a pod of dolphins also joined in on the fun, nose-tapping Deep Blue as a seemingly friendly gesture.

Kayleigh Burns said people have the wrong idea about sharks, after meeting the great white close up for the first time. (9news)

Hawaii waters are usually too warm for great whites compared with California's Pacific coast, where they feed on sea lions and elephant seals. But, when a whale carcass emerges, it brings a range of new wildlife into the waters.

The Hawaii Department of Land and Natural Resources said in a statement that the decomposing whale carcass had drifted about 13 kilometres south of Pearl Harbour after being towed 24 kilometres offshore days earlier.

The department said tiger sharks have been "almost continuously" feeding on the whale and said it was aware of photos of the great white.

The agency's Division of Conservation and Resources Enforcement, Chief Jason Redull, said people should stay out of the water around the dead whale.

The large pregnant mammal was in the waters feeding on a dead sperm whale that had washed in from Pearl Harbour. (9news)

"We don't want anyone to get hurt if a shark swimming around the carcass mistakes them as food. Understandably, some people want to get into the water either out of fascination or to get photographs, but it is truly dangerous to be around this carcass with so much shark activity," he said.

The agency said there are reports people climbed on top of the whale carcass and removed its teeth, which may be a violation of state and federal laws.

Officials said the carcass it is currently drifting away from shore, but a predicted shift in the winds could once again push it back toward Oahu.

Deep Blue is believed to be the largest white shark ever recorded.

Ms Ramsey told local media that big pregnant sharks are often the safest to be around, because they've seen it all and are rarely threatened.

The giant great white was bigger than six metres and was very docile around the intrigued divers off the coast of Oahu. (9news)

Sharks usually only bite when they're curious or mistake people for their natural prey but are unpredictable, she said.