As fall begins, I’m remembering my best summer stunt. It was one of those late-summer Sundays when the only thing to do is swim. I had a particular swim in mind. I got the idea for it during the bleakest days of last winter. When things seemed like they couldn’t get worse, I started to think about swimming across Manhattan—about plowing through every pool on the island. I would be like Neddy Merrill, the protagonist of John Cheever’s story “The Swimmer,” who swims across the suburbs, from one back-yard pool to the next. He swims because he’s lost everything—his social status, his home, his family. He’s delusional and drunk. Actually, I wouldn’t really be like him. My predicament wasn’t comparable. My drinking was under control, for the most part. My swim would be investigative, maybe healing. I spent my childhood in pools: they were like a second womb. A day spent swimming in each of Manhattan’s pools seemed like an obvious move.

In Cheever’s story, Merrill is forced, at one point, to cross a public pool. “It stank of chlorine and looked to him like a sink,” Cheever writes. “A pair of lifeguards in a pair of towers blew police whistles at what seemed to be regular intervals, and abused the swimmers through a public-address system. Neddy remembered the sapphire water at the Bunkers’ with longing, and thought that he might contaminate himself—damage his own prosperousness and charm—by swimming in this murk.” My pool marathon would take place almost entirely in Manhattan’s murk—that is, in public pools. I love outdoor public pools. As I marked the locations of Manhattan’s pools on a map, a constellation emerged: the people’s moat, a secret waterway, a liquid realm. Among the honking taxis, flashing lights, and fretful pedestrians, I would swim.

I started at the bottom—the most downtown pool—which is in Vesuvio Playground, on Thompson Street, in SoHo. There were ginkgo trees, a pretty iron fence. It looked to be a tiny pool. As I reached the deck, a stout woman in a khaki-green uniform stopped me. “Do you have a child?” she asked. I did not. I do not. “This is only for kids!” Now I could see: it was a wading pool. There were children splashing, a couple of dads. Noting my disappointment, I think, the guard said, “But we have a lotta pools for adults around here.” The nearest one, she said, was on Varick and Carmine.

I headed northwest. Three old men were sitting on a stoop across from Father Fagan Park. Orange morning glories climbed toward the hot sun. On Varick Street, a promising-looking three-story brick building appeared, wrapped around the corner at Carmine. The Parks Department’s leaf logo was stencilled on one wall. Three women sat at the entrance. One asked me whether I had my lock. I did not. All I had was a notebook, pens, a map, a MetroCard, and some cash. Nothing is allowed on the pool deck, they said, not even notebooks. Everything must be locked in the changing rooms. I said I’d be quick—just a lap or two. One of the women, a guard, sighed and said she’d stash my little cloth bag under her chair.

The changing room smelled of rubber and chlorine. A frail, very old lady sat in front of a locker in her bathing suit, cocooned in a raggedy white towel. Her hair stuck out from beneath a purple nylon cap, which covered only the top of her skull. I hurried past and walked out to the pool. The cerulean water sparkled. I crossed the concrete deck and threw myself in.

“He had an inexplicable contempt for men who did not hurl themselves into pools,” Cheever wrote. I felt the same way. The water was cool and silky. My arms clasped above my head, I dolphin-kicked underwater, turning my two legs into one strong tail. “Being embraced and sustained by the light-green water seemed not as much a pleasure as the resumption of a natural condition, and he would have liked to swim without trunks, but this was not possible, considering his project.” I pulled my arms down by my sides, then brought them around and out of the water, breaking the surface with a butterfly stroke. I took another stroke, ribboning across the surface, and kicked until I touched the wall. A Keith Haring mural—painted in 1987, three years before he died—danced on a wall above me. A waving figure rode a dolphin, which kissed the shadow-puppeting hand of a king. A fat fish ate a swimmer. A merperson gyrated.

I swam back underwater, and when I came up a lifeguard with curly blond hair was eating a blue ice pop and flirting with another guard in mirrored aviators, who was twirling his whistle around his index finger. A man and his son were lying on a bench set against the brick of the main building, a converted public bathhouse. Two scraggly pigeons cooed.

Back in the locker room, the old woman hadn’t moved. I grabbed my bag from the guard. “You were quick!” she said. I pulled on shorts, found a Citi Bike, and headed east on Houston. A posse of tatted and tanked boys sauntered past, looking like they had something to prove.

The Hamilton Fish Park Pool, which is on Houston Street just below where Avenue C begins, was one of eleven pools to open across the boroughs in the summer of 1936. Eleven! Robert Moses, who swam at Yale, had just become the city’s Parks Commissioner, and he and Mayor Fiorello LaGuardia worked closely with the federal Works Progress Administration. Some of the W.P.A. pools are magnificent. The Hamilton Fish pool is colossal; it was used by the U.S. Olympic swim team for a training session in 1952, before they headed to Helsinki. A sign there says that the W.P.A. pools changed “the way millions of New Yorkers spent their leisure time.”

I left my bag with the guard (“no problem, no problem”) and, yes, hurled myself into the water. I followed a black line that ran across the bottom for fifty metres—nearly a hundred and sixty-five feet—lengthening my stroke as I swam. Across my path, there were underwater legs running in slow motion, as if the beat of the world had slowed. Girl legs chased boy legs. The sounds of shrieking, laughter, and lifeguards’ whistles were all muffled. The water refracted the light. A woman with a snorkel dived in front of me. I dodged her and continued, stretching out, settling into an easy freestyle. The water was refreshing, cool but not cold. At the wall, I flip-turned, swam back, and got out. Two lifeguards in orange shorts were leaning against a fence. One exhibited the usual tic, twirling her whistle around her index finger. A teenage boy with a scruffy beard and a tattoo of a heart over his heart was peppering her with questions while his friend stood by silently. “It seems like it’s a good job for a young person, right? How far can you swim underwater? Where do you train? How much do you get paid?” (First-year guards get $13.57 an hour.)

Citi Bike returned, I walked north up Avenue C. Cold air wafted out of an Associated Market. Sixth Street smelled like fried chicken. On East Tenth Street, I found the Dry Dock Playground pool. (This neighborhood was known as the dry-dock district in the nineteenth century, when it was filled with bustling ironworks and shipfitters.) Trees and grass were sparse. Fence, concrete, water. I swam a lap in ten seconds. The Jacob Riis Houses towered to the north. Lifeguards blew their eternal whistles, one after another, in a circular, comforting way, the sound of soccer games ending, thunderstorms arriving, marching bands parading, a summer night. “Everyone out!” they yelled. It was their afternoon break. Outside the pool fence strolled an old man with his pocket radio tuned to a baseball game.