Jester was recruited by the U.S. Navy to dive to great depths and find objects in the ocean, everything from undetected mines to air crash victims.
But Jester didn't make the grade and was mustered out in San Diego.
Now he's a tourist attraction at the Aquarium of Niagara.
"He was afraid of the ocean," said Jennifer Humphrey, the aquarium's supervisor of marine mammals.
The 4-year-old sea lion was born at Sea World of Florida in Orlando and was raised by humans. After a three-year stint in the Navy, he was acquired by the aquarium and flown to Niagara Falls in a C-130 military transport Dec. 4.
He spent two weeks in quarantine and began swimming in the main tank a week ago.
"He seems content to make his home here," said Humphrey. "He's got some adjusting to do, but we hope he will be the star of the show one day."
The 275-pound youngster is already a big hit with visitors to the Whirlpool Street attraction.
"I see a lot of smiles on people's faces," Humphrey said. "He's a pretty playful guy."
The neutered male shares the 100,000-gallon main tank with three female sea lions -- Squirt, Julie and Diamond, each about 20 years old.
"They're still wary of each other," said Humphrey. "There's a lot of barking and open-mouth challenging, but they appear to be adjusting."
Jester is the first sea lion acquired by the Aquarium of Niagara in 15 years, aquarium spokeswoman Gay Molnar said.
The Navy has been recruiting sea lions and other marine mammals, such as dolphins, seals and whales, for many years to do what humans cannot -- dive as deep as 500 feet to find and retrieve things.
Those mammals can hold their breath longer than humans and don't require expensive diving equipment.
But Jester wasn't cut out for the job. Humphrey learned of the sea lion's case through the International Marine Animals Trainers Association and took a flight to San Diego with the Aquarium of Niagara's veterinarian, Ed Larson.
The Navy put them all on a C-130 and flew them to Niagara Falls Air Reserve Station. Jester was calm during the 6 1/2 -hour nonstop flight, Humphrey said.
Now that he's back in civilian life, the new Whirlpool Street resident is eating well -- about 20 pounds of fish a day -- and working toward a career in show business.
"If you see a sea lion with a Frisbee in his mouth," said Humphrey, "that'll be Jester."