It’s spring in New York City. At Twenty-sixth and Park, the waves shine in the sunlight, and the breeze is briny with seaweed. Morning commuters are boarding a crosstown vaporetto. Out on the canal, finance guys in speedboats weave between the bigger ships. Workers in an inflatable raft are repairing the Flatiron dock; a superintendent, in diving gear, is checking his buildings for leaks. The super-rich live uptown, in a forest of skyscrapers near the Cloisters. The poor live downtown, in Chelsea, which is half-submerged.

This is the vision of the city in “New York 2140,” a science-fiction novel by Kim Stanley Robinson, out last month. It’s surprisingly utopian. New York may be underwater, but it’s better than ever. Sure, it was a rough hundred years for the planet: the seas rose ten feet in the two-thousand-fifties, then forty feet more around 2100, and billions of people died. Each episode of flooding was “a complete psychodrama decade, a meltdown in history, a breakdown in society, a refugee nightmare, an eco-catastrophe, the planet gone collectively nuts.” Now, though, New York is the “SuperVenice.” Downtown, in the “intertidal” zone (it’s submerged at high tide, but otherwise walkable), the rent is—understandably—low. Artists squat in half-drowned buildings and drink in speakeasy bathhouses; the office towers of midtown have been turned into apartments with their own docks, dining halls, and rooftop farms. You can commute by boat or by walking through one of the city’s “skybridges” (basically, big plastic tubes reinforced with graphene). As one of the book’s narrators explains, “Yes, people returned to the drowned parts of New York. Actually many of them had been living in such shitholes before the floods that being immersed in the drink mattered little. Not a few experienced an uptick in both material circumstances and quality of life.”

“New York 2140” is told from eight different perspectives. One of its narrators, Franklin Garr, works at a hedge fund called WaterPrice; he’s the creator of the Intertidal Property Pricing Index, which allows investors to price drowned assets. No one knows exactly what half-submerged buildings are worth—the seas could rise again—but Garr’s I.P.P.I. makes it possible to buy derivatives based on underwater mortgages; as a result, a new housing bubble is underway. (“Now as always you could get AAA ratings, not for subprime mortgages, obviously bad, but for submarine mortgages, clearly much better!” he explains.) Garr meets girls at waterfront bars, takes them out on his boat, grills steaks on a little hibachi, and drinks rosé while trying to figure out which neighborhoods will “regentrify” next. The revitalized New York, to him, is “fashionably hip, artistic, sexy, a new urban legend.”

Another narrator—a nameless urban historian—tells the story of New York from a bohemian point of view. America’s boring losers all moved to Denver, he says, and so the cool kids took over the coasts. “Squatters. The dispossessed. The water rats. Denizens of the deep, citizens of the shallows.” The abandoned city becomes an experimental zone—a place where social innovation (“submarine technoculture,” “art-not-work,” “amphibiguity”) flourishes alongside “free open universities, free trade schools, and free art schools. Not uncommonly all of these experiences were being pursued in the very same building. Lower Manhattan became a veritable hotbed of theory and practice, like it always used to say it was, but this time for real. . . . Possibly New York had never yet been this interesting.”

Many of the pleasures of “New York 2140” are architectural. Robinson points out that the Met Life Tower, where all the characters live, was modelled on the Campanile, in Venice, giving Madison Square the look of Piazza San Marco. He’s figured out which neighborhoods will be submerged (the East Village, Hudson Yards) and which will be aboveground (the new developments are happening in Yonkers). Reading “New York 2140,” I learned that, if the sea level rises fifty feet, it might be possible to surf from Herald Square to Central Park: as the tide rushes up both Broadway and Sixth, it will flow together to create a wave. Robinson vividly imagines everyday life in such a place. During summer, future New Yorkers look down through the water to aquaculture pens, where fish churn; during winter, the canals freeze—temperatures in the future are more extreme—and people can go ice-skating, as long as they avoid the holes in the ice where harbor seals and muskrats come up for air. (“It was as though the streets had come back,” one woman thinks.) You know spring has arrived because of “a huge cracking noise”—the ice in the East River breaking up.

Robinson, who is sometimes described as our greatest living utopian writer, has spent most of his life in California. He was born in 1952; he holds a Ph.D. in English literature, and his adviser in graduate school, where he wrote a thesis on Philip K. Dick, was the Marxist theorist Fredric Jameson. Many of Robinson’s novels imagine, in detail, the practical habits of environmentally responsible and economically just societies. In “Aurora,” which came out in 2015, interstellar explorers realize that living on other planets is impractical, and return to Earth. In “2312,” humanity has spread throughout the solar system with the help of a new kind of economy—a “mondragon,” or vast, coöperative corporation, centrally planned by quantum computers. (The term comes from the Mondragon Corporation, a real and vast Spanish company that is owned by its seventy-five thousand employees, who manage it and manufacture appliances, auto parts, and other goods.)

Like Robinson’s other novels, “New York 2140” is packed with political and economic details—it reads, in places, like the Metro section of the Times. Middle-class homeowners have banded together to form a “Householders Union.” Apartment buildings are environmentally self-sufficient, with solar panels, gardens, and even livestock floors. The Lower Manhattan Mutual-Aid Society, known as “lame-ass,” coördinates the sharing of resources during storms and other emergencies. The rich are ensconced in their skyscrapers, but everyone else lives in some form of commune. Many people have been displaced by climate change and “radicalized by their experiences”; they blame global warming on financiers, and on a market system that consistently underestimates the environmental costs of economic growth. The book is, among other things, a sustained critique of capitalism. After the oceans rise, the system’s central flaw is obvious and undeniable: the market “is always wrong,” one man says. “The prices are always too low, and so the world is fucked.”

The catastrophe in “New York 2140” is unprecedented, but the book’s world-weary New Yorkers still feel as if they’ve seen it all before. They’re keenly aware that their city has always been a destination for refugees fleeing disaster. The story of New York, after all, is that a bunch of people whom no one wanted created the coolest city in the world; eventually, their cultural capital was turned into real capital, sometimes by them, but often by outside investors. “Wait and see what those crazy people did with it, and if it was good, buy it,” one man says, describing the attitude of global finance to post-climate-change New York. “As always, right? You brave bold hip and utterly co-opted avant-gardists, you know it already, whether you’re reading this in 2144 or 2312 or 3333 or 6666.” The joke is that, even as history repeats itself, things seems to get worse each time; New Yorkers may excel at making love among the ruins, but enough with the ruins already. After the underwater-housing bubble bursts and a Sandy-like superstorm plunges the city into chaos, the plot turns on the question of whether the government will finally nationalize the banks. Despite everything they’ve been through, their utopian imaginations remain undimmed. In the end—in ways best left undescribed—the New Yorkers of the future stand up to the system and change it.

Parts of “New York 2140” are familiar. In one scene, workers put on diving gear to check on a sandbar they’re building near Ocean Parkway: in their headlamps, they see the submerged remains of Brooklyn, including “an armchair, resting on the bottom as if a living room had stood right there.” It’s the kind of uncanny, elegiac image we’ve seen in a thousand dystopias. What distinguishes Robinson’s novel is its vitality, its sense that life goes on. Today’s New Yorkers get a charge out of living amid the city’s history of struggle. Similarly, New Yorkers in 2140 love “motoring across the shallows of the Bronx,” dodging “roof reefs.” Watching waves break against the submerged apartments of Coney Island, they feel alive. They’re just like us, in other words. If they can fight climate change, why can’t we?