I like a phrase that seems to have originated with Ken Greenberg, an architect and urban designer from Toronto: “The melting of the industrial glacier.” The single biggest change to the physical fabric of the city since the RMS Queen Mary last sailed out of town is surely the transformation of the waterfront.

New York’s not alone in this, obviously. City waterfronts have been changing everywhere, often hand in hand with private development. If anything, the pendulum may have swung too far. Public-private partnerships have many benefits but they always come at some cost, and cities also need industry and economic diversity.

That said, these three new parks are good news, especially at a time when Mr. de Blasio, primarily focused on existing parks, has announced no big plans of his own for new parks and still has yet to decide how to redo miles of critical parkland along the East River in Manhattan, where Hurricane Sandy devastated a number of public housing projects. More storms will come. Waters are rising.

And so is the city’s population, driving up the demand for open space.

That’s clear from how swiftly these latest waterfront parks have been adopted.

At Brooklyn Bridge Park, one of the city’s most crowded parks already, Pier 3 adds 4.5 acres of breathing room, sandwiched between soccer fields and basketball courts. The architect, as he has been for the entire project, is Michael Van Valkenburgh. In a park that he devised to be mostly extroverted, stressing recreation and views, he conceived the new pier as an interlude and inward-looking. Frederick Law Olmsted, the father of American landscape architecture, described the beckoning pleasures of a curved path, offering up surprise and a chance encounter around the corner.