Watch Giant Whale Circle Tiny Fishing Boat: 'Completely at Its Mercy'

A video shows a huge whale estimated to be more than 20 feet in length circling a fishing boat in a fascinating close encounter.

Tamanui Uerata and two friends came into contact with the whale this past Friday after setting off in their boat from Kaiteriteri, a coastal town on New Zealand's South Island. The trio had anchored in Tasman Bay just off the coast and were hoping to catch some kingfish—a large fish found in the Antarctic Ocean—not realizing that they would be in for a big surprise.

At one point, the group heard a big splash behind the boat, which they initially thought might have been caused by a kingfish. In response, they threw a few lures out.

But they quickly discovered that the disturbance had not been caused by a fish at all but by a large whale, with the giant creature surfacing just a few feet away from the boat.

"When I first saw the whale, I was simply in awe—the grace in which it moved about, the size of it," Uerata told Newsweek. "Such a beautiful creature."

After the initial amazement of seeing the whale, which they assumed to be a humpback, the trio began to worry when they realized how large it was.

"We first became concerned when we realized the width of the tail was more than the width of our 5-meter [16-foot] boat," Uerata said.

"At one point, it swam directly underneath us from front to back," he said. "Its head came up behind the boat while its tail was still in front of us."

The men thought the whale would be able to easily flip the boat with its huge tail if it wanted to. But in the end, the group got lucky.

The whale then began circling the boat and managed to get itself caught on Uerata's fishing line and the anchor line, "easily" turning the vessel.

"That's when the panic set in and we truly realized the power of the animal," he said. "It had turned us and was still moving as gracefully as before."

The whale continued swimming around for a few more minutes, but eventually the lines slipped off and the group fled the area.

"We were completely at its mercy," Uerata told the New Zealand website Stuff. "Whatever this whale wanted to do with us, it was going to do."

The identity of the whale species that the men saw has not yet been verified. But Daren Glover, general manager of environmental organization Project Jonah, told Stuff it was likely a humpback whale or a southern right whale.

Both of these large whale species are known to swim past and come close to New Zealand's shores. But it is quite unusual to see either in the country's coastal waters at this time of year, Glover said.

"They would normally be further south, and being in the Tasman Bay, we hope it can find its way out," he said.

Uerata told Stuff that he had never seen anything like this in more than 10 years of recreational fishing in the area and described the experience as "amazingly freaky."

"This was different lol real different," the fisherman said in a Facebook post following the incident. "At the time excitement turned to nerves real quick but looking back now was something I'll never forget. The boys freaking the f*** out but also just seeing how graceful that creature was."