KAUNAKAKAI, Hawaii -- For months now, a baby monk seal named KP2 has been the biggest celebrity on the island of Molokai.

Since the animal arrived at Kaunakakai Wharf in February, several children from the island have made a habit of swimming with him. Area paddlers and boogie boarders have shared laughs watching him climb into or onto their boats and boards. One resident was so comfortable with KP2 that he put his golden retriever in the water with the seal and documented it in a YouTube video.

KP2, an endangered Hawaiian Monk Seal, is so tame you can swim with him ... but not for long. WSJ's Chris Herring reports.

But now that KP2 calls Molokai home, he is likely to be sent away any day now. That's because the 17-month-old pup is maturing. His weight, now 175 pounds, has more than doubled since spring, and he has begun playfully grabbing swimmers from behind with his flippers.

Seal experts worry that KP2 risks loving people to death. "We've had experiences before where a 300-pound animal is just looking to play and then starts holding people underwater for too long. And with how much KP2 likes being around people, we think he's bound to get to that point," says Wende Goo, a spokesperson for the National Oceanic and Atmospheric Administration.

For safety's sake, NOAA officials are planning to have KP2 sent far from Molokai as early as this week. Some Molokai islanders, however, are determined to keep him. "If they ship KP2 off the island, it might get ugly here. There'd be an uproar," says Darrin Abell, owner of Paddlers' Inn restaurant, which is less than a mile from the seal's favorite hangout.

KP2's popularity in Molokai stems from the fact that he doesn't seem to know he's a seal. He has spent most of his life surrounded by people. His mother rejected him at birth, and oceanic specialists rescued him less than 24 hours after he was born. NOAA, along with the Marine Mammal Center, raised him for nearly eight months.

KP2, raised in captivity, prefers to spend time with humans near Molokai's Kaunakakai Wharf. Val Bloy

Three months after he was released into the wild, KP2 swam to the southern shore of Molokai and started befriending wharf dwellers. He was welcomed into a community of 7,000 people where entertainment comes mostly from the sea. There are no movie theaters or shopping malls to serve as distractions.

When NOAA first realized KP2 was playing with people at the wharf, the agency moved him 40 miles away. But just two days later, KP2 was at the wharf again.

To some residents, that meant he belonged in Molokai. "If they take him away one more time and he comes back, I don't think this community will let NOAA take him again," says Walter Ritte, executive director of the Hawaiian Learning Center, a nonprofit outfit that teaches local children about Hawaii's ecology.

Karen Holt, executive director of the Molokai Community Service Council, has been considering how the seal might be kept on the island. She has called local animal trainers to see whether KP2 can be deprogrammed to stop being so playful around human beings, but experts say it's too late.

Already, there have been reports of KP2 playfully pulling people underwater for seconds at a time. Ingrid Toth, a small, white-haired 70-year-old woman, had been swimming with KP2 every day for about half an hour until a couple of weeks ago, when the monk seal held her under the water from behind for about five seconds. Ms. Toth says that, for a moment, she was frightened. "It made me think that one time, he may just keep me down there."

Yet, Ms. Toth is one of the residents who is most adamant that KP2 should be allowed to stay on the island.

Officials, worried KP2 will grow too big to safely play with people, plan to move him 200 miles away Val Bloy

NOAA officials have seen this fight before. David Schofield, a marine mammal response coordinator for NOAA, recalls another seal -- named RO42 -- that stumbled upon people and began playfully grabbing them with her flippers. But as RO42 got older, she began pulling people under the water and in one case, broke somebody's skin with her love bites. RO42 garnered even more attention when she blindsided the actor William Shatner, who was swimming nearby, and assaulted him. Mr. Shatner made humorous reference to the incident on "The Late Late Show With Craig Ferguson" earlier this year. "The monk seal species, I believe, is endangered...but the Shatner species, I know, is endangered," Mr. Shatner says.

Some people say NOAA created the problems with KP2 -- that it's only natural that a seal raised by people would want to be around people. "NOAA has scientists that make $100,000 a year, so why don't they understand cause and effect?" says Robert Wilt, a wharf denizen who goes by nickname "Stretch."

NOAA officials say they realized that human interaction could make the seal behave differently from one raised by his birth mother. "It was a very real concern for us, and we anticipated this as a problem," says Mr. Schofield. Indeed, scientists often give monk seals android-sounding names to reinforce the idea that the animals aren't human. (Islanders want to hold a contest to give him a new name.)

NOAA plans to move KP2 about 200 miles away to just south of the Northwestern Hawaiian Islands. The distance likely would be too far for the seal to swim back, but if he does, the federal agency will then put KP2 in an aquarium or sea park, neither of which Molokai has.

NOAA officials, preparing for the difficult task of having to explain to island children KP2's move, have been dispatching Christine Smith, a volunteer teacher with a background in marine biology, to talk with kids. Ms. Smith suggested framing the KP2 sendoff as a "graduation from Molokai." Children would write valedictory speeches about KP2.

Ms. Smith faces a skeptical audience. Eleven-year-old Liwai Basa, who swam with KP2 many days over the summer, rejects the notion that the seal is dangerous. "It's not," he says.

Mr. Schofield says he can understand how being separated from KP2 can be a tough thing for people who have come to love him. But, he says, "It always starts out, 'Don't take our seal!' Then, as soon as it starts getting too rough, people are yelling at me, 'Come get your seal!' I really don't want to be in a position to say 'I told you so' this time."

Write to Chris Herring at chris.herring@wsj.com