It would be a bold addition to the Manhattan waterfront — a $170 million, futuristic park built atop an undulating platform 186 feet off the Hudson River shoreline with a series of wooded nooks and three performance venues, including an amphitheater.

The offshore park near 14th Street might be considered fanciful were it not for its sponsor, the billionaire Barry Diller, an important figure in the television, film and Internet industries. To oversee events, Mr. Diller has recruited powerful partners, including Scott Rudin, the film and theater producer.

Mr. Diller, the chairman of IAC/InterActiveCorp and former head of Paramount Pictures and Fox, has agreed to provide $130 million to build the park through a family foundation; an additional $39.5 million would come from the city, the state and the Hudson River Park Trust.

“I have always loved public spaces,” he said. “It’s entirely my fault that this has become so ambitious. We will fail in our ambition, outsized or whatever it may be, if this doesn’t feel completely like a park and completely like a performance space.”