When Jimmy Hall realized he was within mere feet of a great white shark, he did not swim away. Instead, he left the safety of a shark cage off Hale'iwa and swam with the beast.

He even reached out and touched it.

"It's been a dream of mine for many, many years to swim with a white shark and I got to do it. And I got to do it with one of the biggest ones that I've ever seen, even in photographs," Hall said.

Hall is a captain with Hawai'i Shark Encounters, a tour company based in Hale'iwa. The company takes customers three miles off Hale'iwa, where they spend a couple of hours in a cage, hoping to see sharks.

On Wednesday, Hall accompanied seven customers who had been in the water for about an hour when there was a commotion in the cage.

"People in the cage started yelling about the enormous shark that they saw," Hall said. "As soon as they started yelling, we saw this incredible shape coming up. I thought it was a small humpback whale, that's how big it was. It was so big that I didn't even think that it could be a shark."

Hall quickly realized he was staring at an 18- to 20-foot female great white shark, one of the most feared creatures of the sea. He said it was the first time since he's been involved in the shark diving business that a great white has appeared.

Hall didn't want to miss his opportunity, so he jumped in with his customers. But after a few minutes he decided get out of the aluminum cage to be closer to the shark.

Hall said he got close enough to touch the shark "many times."

"I was scared, not petrified, and a lot of it was a thrill, just in realizing how special this was," he said. "But you're not going to face something that big and not be scared."

John Naughton, a biologist and shark expert with the National Marine Fisheries Service, has seen the video of the encounter with the shark and said it "was a very magnificent animal." Naughton estimated the shark to be at least 17 feet long. He said the largest great white recorded was 21 feet.

Hall said the shark was very calm — and described the experience as incredible. In the 45 minutes that the shark was there, it rubbed against the boat and cage several times.

"It sounds silly to say, but she looked really friendly, rubbing against the boat, never really aggressive," Hall said.

The shark's presence excited the tour group, but Hall said they quickly settled down.

"They understood what they were seeing, that it was something really, really special," Hall said.

One of the passengers was Richard Parry, a Wai'alae Nui resident, who took the tour with his 23-year-old son Robert. Richard Parry said he was on the boat when the shark appeared.

"We were just expecting to see some of the local sharks, maybe a hammerhead or a tiger if we got lucky, and then suddenly all these sharks disappeared, and this girl who was in the cage yelled out, 'Oh, my God, there's the biggest shark I've ever seen,' " Parry said. "We thought she was exaggerating and the tour guide sort of said, 'I think it's a baby humpback.' And then he looked and said, 'Oh, God, it's a great white.' "

The Parrys quickly jumped into the cage. Richard Parry said he never was afraid of being in the water.

"My initial reaction was one of amazement, that it was there, and a little bit of, 'This thing is a man-eater.' But I didn't feel threatened," he said.

Unlike Hall, however, Richard Parry never considered getting out of the cage to be closer to the shark.

"It goes through your mind, and then you think, 'Nah, I'm not going to do that,' " he said.

Naughton said great whites are rare in Hawai'i because they prefer cold waters, and there isn't a concentrated food source like there is off Northern California, where seals migrate. He said there have been many great white sightings here over the years, but the footage of the one seen Wednesday "is the best I've ever seen."

In clear ocean, great whites don't usually attack humans, Naughton said. "They just don't recognize us as a food source," he said.

Still, Naughton said, he wouldn't recommend that anyone do what Hall did.

"It's very dangerous for somebody to be in the water with them, because if they wanted to, a thing that size could have cut Jimmy in half in one bite," Naughton said.

"But I don't blame him. He was so excited, and he's been in this business for so many years, and this is something new and exciting."

Reach Curtis Lum at culum@honoluluadvertiser.com.