Tennis is the loneliest sport, Andre Agassi has said. I wonder if he has reckoned with the solitude of competitive swimming.

The talented illustrator Leanne Shapton, in her pointillistic and quietly profound new memoir, recalls how, in 1988 and 1992, specializing in the breaststroke, she made it as far the Canadian Olympic trials. Shapton writes as confidently as she draws, memorably conjuring swimming’s intense, primordial and isolating pleasures.

She describes the sensation of being underwater and alone at a meet, the “loud then quiet, loud then quiet” of one’s head rising above the waterline, how “a chorus of warbled pops and splashings bursts against the sides” of your cap. She notes how swimmers are made to feel not merely solitary but quite small. “Coaches stand above you, over you,” she writes. “You look up to them, are vulnerable, naked and wet in front of them.”

Shapton is the author and illustrator of several previous books; she is also the former art director of The New York Times’ Op-Ed page. With Swimming Studies she has composed a volume that is less a proper memoir than a collection of flickering sketches. It leaps from her training for the Olympic trials and becomes a treatise on swimming and pools in general. It’s a sport that lingers in her mind and in her muscles.

“I still dream of practice, of races, coaches and blurry competitors,” she says. “I’m drawn to swimming pools, all swimming pools, no matter how small or murky. When I swim now, I step into the water as though absent-mindedly touching a scar.”

Her book is sprinkled with her own spare illustrations, like the two pages of small ovals that represent odors she recalls from her swimming days. Her prose frequently has the density of poetry. She notes how swimmers have the ability to “make still lifes out of tenths of seconds.” Boys at work making pool lanes are “a mini Iwo Jima tableau.”

In time for this summer’s Olympic Games, her book is also a canny insider’s look at competitive swimming, a sport she describes as “insular, clammy, circumscribed and largely underexposed.”

She walks her readers through changes the sport has undergone since her time, like the arrival of “technical suits, track blocks, false-start rules.” She notes that the inverted-V formation that occurs in most races is because the fastest racers are placed in the middle, while the slowest are at the outside. “A swimmer who leads from lane one, two, seven, or eight,” Shapton observes, “is often called ‘outside smoke.’”

Shapton’s book contains its own kind of outside smoke. She pulls in unusual elements, odd stray memories. She writes about how Alcatraz and the Titanic disaster interest her from a swimming perspective. She imagines breast-stroking away from each.

Some readers may find that Swimming Studies verges on the precious. It’s an adorable book, self-consciously so, a boutique item that cries out to be sold on Etsy and next to the garlic scapes at organic farmers’ markets. But Shapton is so smart and so likable that you will pass her book along to the swimmers in your life. Her experience underscores the truth of a T-shirt slogan she spies at a competition: “If swimming were any easier, it would be called hockey.”

Dwight Garner reviewed this book for The New York Times.