When the museum that occupies Doris Duke’s opulent Black Point home erected a 6-foot fence along its Cromwell’s sea wall two years ago, officials were hoping to put a serious dent into the growing level of dangerous ocean horseplay there.

But that didn’t happen. The jumping and diving into a former boat basin not only continued, it actually increased, with some of the most daring individuals taking a riskier leap from the top of the new fence.

Now the Doris Duke Foundation for Islamic Art is going a significant step further by proposing a $2.5 million plan to dismantle the basin’s breakwater built by Duke in 1937 and transform the armored shore into a more natural rocky coastline similar to surrounding areas.

Museum officials said they hope the project finally and dramatically reduces the dangerous activities on the shore in front of Shangri La.

“We don’t want to get in the way of fun,” said Konrad Ng, the museum’s executive director, “but we do want to stand up for safety.”

The Shangri La Breakwater Safety Initiative and Shoreline Stabilization Project is described in a draft environmental assessment filed with the state Office of Environmental Quality Control. A public comment period will close Dec. 8.

Shangri La is the former home of “the richest girl in the world,” the heir to the fortune of her father, tobacco magnate James Buchanan Duke.

An art collector and philanthropist, Doris Duke built the posh residence at the foot of Diamond Head between 1936 and 1938, filling it with rare and spectacular artwork inspired by her travels to Africa, Asia and the Middle East.

When she died in 1993, Duke left instructions to have Shangri La opened to the public for the study of Islamic art and culture. It did so in 2002, offering guided tours, lectures, performances and programs.

During the construction of Shangri La, Duke sought and received permission from the Territory of Hawaii to build a sea wall and yacht basin protected by a breakwater. The area would become known as Cromwell’s, which was her first husband’s surname.

While the basin was initially used for vessel berthing, it evolved into a recreational area, a magnet for swimming, snorkeling, shoreline fishing and access to surf sites. For decades the area’s young people gravitated to the spot.

In recent years, however, the area’s popularity has soared, with high-risk jumping and diving seemingly the featured attraction, thanks in part to social media and travel websites, said Lea Major, deputy director of the museum.

At least one person is known to have become a quadriplegic, Major said, while two others became paraplegic due to injuries suffered from jumping into the basin.

According to the draft environmental assessment, an average of 925 incidents per month of people jumping from the sea wall and the breakwater were recorded in 2013 and before the construction of the fence in May 2014.

With its vertical bars, the $160,000 black aluminum fence was designed to prevent people from using it as a platform for jumping.

But they still find a way.

The new plan calls for using the boulders from the breakwater, along with others, to stabilize and reinforce the sea wall. The breakwater was built over a natural rocky dike, and much of that should remain viable in the surf.

The breakwater on the Koko Head side of the property will not be touched, nor will the stairs that descend into the surf. Access along the shore will be maintained.

“We have explored many options to reduce dangerous activity at Cromwell’s and have determined that restoring the shoreline to a more natural state is the best option,” Ng said.

Additionally, the project’s newly reinforced sea wall in the long run will help the property cope with sea-level rise due to climate change, he said.

Once the foundation gets the necessary approvals, the construction phase of the project is expected to take six to nine months.

A 31-year-old who was swimming in the boat basin with a friend Thursday said he was sad to hear about the museum’s plans, although he can understand why they would consider it.

Declining to give his name, the man said he has been visiting the spot since he was 10 or so, and over the years he’s witnessed some reckless behavior, including people using ladders to jump into the water.

“I see where they’re coming from,” he said of the museum. “People would rage out here. High school kids would be drinking and smoking weed. They screwed it up for everybody else.”