A New Jersey doctor built his own island. It’s now on sale for $16.5 million.

A 1.4-acre private island just went on sale in Florida, complete with a 3-bedroom house, a swimming pool, and a cistern to collect drinking water — asking price $16.5 million.

You’re thinking it was built by a movie mogul, perhaps. Or a tech billionaire?

Try a gastroenterologist from New Jersey.

Back in the 1970s, Klaus Meckeler was among the first physicians in the United States to use specialized endoscopes for examining the bile and pancreatic ducts. But when not working at his practice in Somerset County, his mind often strayed to his pet project in the Florida Keys, son Kai Meckeler recalled.

“My dad was a romantic,” he said.

The island is located a quarter-mile offshore from the Florida Keys. When the physician first saw it, it was just a pile of rock jutting from the water, his son said. A previous owner had excavated a moat from the coral rock and piled the debris in the center, intending to use it as a place to raise monkeys for scientific research, but the plan fell through, the younger Meckeler said. (The excavation likely would not have been allowed under current environmental regulations.)

Klaus Meckeler bought the property for $25,000, and took on the challenge of turning it into a habitable island. He hired contractors to level off the volcano-shaped pile of rock, using construction equipment that was ferried out to sea by barge. Builders piped fresh water out to the site to make concrete for the foundation, his son said.

The house was finished by 1979, and the Meckeler family often went there for vacation.

In New Jersey, Meckeler was the chief of gastroenterology at what was then Somerset Medical Center, in Somerville, now called Robert Wood Johnson University Hospital Somerset. Born in Germany, he attended medical school there before coming to practice in the U.S. in 1958.

He traveled to Japan to study ERCP, the new endoscopy technique for the bile and pancreatic ducts, and taught others to do it back in the U.S. Later in his career, he became a clinical professor at Robert Wood Johnson Medical School.

Meckeler, who died in 2008, sold the island, called East Sister Rock Island, in 1995 for $750,000 to the Williford family, the two families said.

The Willifords undertook substantial renovations, including installing a solar-panel array and adding a wind turbine with battery storage, said Wesley Williford, a family member who is also the real estate agent on the new listing. The family also added central air-conditioning and a desalination plant with the capacity to make 1,000 gallons per day, and turned it into a full-time vacation rental, he said.

Will they get their $16.5 million asking price?

Kai Meckeler, the son of the doctor who created the retreat, has his doubts, but says the property has unique appeal.

“Everybody thinks they want to own an island,” he said. “It’s just not for everybody.”

EDITOR’S NOTE: This article has been updated to reflect that the current owners installed a solar-panel array. There were no solar panels when they purchased the island in 1995.