Why We Swim

Bonnie Tsui is a journalist, essayist, and lifelong swimmer whose nonfiction book blends memoir, cultural history, and science writing to investigate a deceptively simple question: Why do humans swim? Organized into five thematic sections, Survival, Well-Being, Community, Competition, and Flow, the book travels from prehistoric Saharan lakes to Icelandic swimming halls, from Baghdad war zones to Japanese martial arts pools, arguing that swimming is far more than exercise. It is survival, medicine, communion, contest, and a portal to an altered state of mind.

The book opens with Guðlaugur Friðþórsson, a 22-year-old Icelandic fisherman whose trawler capsized in the frigid North Atlantic on March 11, 1984. Guðlaugur lost all four crewmates to drowning or hypothermia, then swam more than three and a half miles through 41-degree water over six hours, arriving on the island of Heimaey with no detectable pulse yet no signs of hypothermia. Researchers determined that his body fat was two to three times normal thickness, giving him seal-like insulation; many called him a selkie, the half-man, half-seal figure of Icelandic lore. Tsui uses his story to frame humans as land creatures with an aquatic past. She establishes herself as a participant too: She learned to swim at age five on Long Island and, after a near-drowning in the shallows, went right back into the water.

In the Survival section, Tsui traces swimming's archaeological record back 10,000 years to the Cave of Swimmers, Neolithic paintings discovered in the Sahara in 1933 by Hungarian explorer László Almásy depicting figures in underwater poses from a period when the desert was green and dotted with lakes. She visits paleontologist Paul Sereno at the University of Chicago, who describes Gobero, a Stone Age cemetery in Niger near what was once a vast shallow lake system. Its inhabitants dived for clams, fished with harpoons, and speared Nile perch. Among the finds was the "Stone Age Embrace," a triple burial of a woman and two children with intertwined hands and flowers beneath them, which Sereno believes resulted from a sudden drowning.

Tsui examines why humans must be taught to swim when most mammals do so instinctively. Drawing on evolutionary biologist Joseph Henrich's work on culture-gene coevolution, the mutual shaping of inherited biology and learned culture over time, she argues that humans' capacity for cumulative social learning explains how swimming knowledge has been transmitted across generations. She profiles the Bajau and Moken sea nomads of Southeast Asia, whose cultures demonstrate both genetic and learned aquatic adaptations. The Bajau have evolved spleens 50 percent larger than those of related mainland populations, providing extra oxygenated blood for deep diving. When the 2004 Indian Ocean tsunami killed some 230,000 people, Moken communities survived by reading ancestral signs in the water, drawing on oral legends about catastrophic waves called laboon. Tsui argues that these storytelling traditions encode critical survival knowledge.

Tsui travels to Heimaey to meet Guðlaugur, who rarely speaks to journalists but agreed to correspond with and meet her, and to participate in Guðlaugssund, an annual commemorative swim held in his honor. She describes Iceland's swimming culture: mandatory instruction since 1943, geothermally heated outdoor pools that serve as communal gathering places, and one of the world's highest ratios of pools per capita. Guðlaugur tells her that the surviving crew members promised whoever lived would work for better safety. She closes the Survival section by interweaving her family history: Her parents met in a Hong Kong swimming pool in 1968, and swimming was the one thing that held her fractious family together. Swimming, she argues, enables survival in ways beyond the physical.

The Well-Being section opens with marathon swimmer Kim Chambers, who began swimming as an adult in 2009 to rehabilitate a leg she nearly lost to amputation after a fall. Chambers joined the Dolphin Club in San Francisco's Aquatic Park and became one of the world's best open-water swimmers, eventually becoming the first woman to swim solo from the Farallon Islands to the Golden Gate Bridge. Tsui traces the history of water as medicine from Benjamin Franklin's Thames swims through pre-Civil War water-cure clinics. Longevity researcher Dr. Hirofumi Tanaka tells her that swimming reduces blood pressure by nine points more than land-based exercise. Tsui describes shedding her wetsuit for her first open-water swim in San Francisco Bay, experiencing shock, euphoria, and then a punishing afterdrop, the continued drop in body temperature after leaving cold water. She reflects that swimming in open water serves as a confrontation with mortality. Chambers's swimming evolves from rehabilitation to activism: She leads the first team to swim across the Dead Sea to highlight climate cooperation and organizes a 2017 border swim from San Diego to Tijuana.

The Community section introduces "Coach Jay" Taylor, a US Foreign Service cultural attaché in Baghdad from 2008 to 2010, who began teaching swimming lessons in one of Saddam Hussein's palace pools after spotting a colleague flailing dangerously in the water. Jay formed the Baghdad Swim Team, which grew to more than 200 students from dozens of countries. He treated every swimmer the same, creating an egalitarian culture where rank, nationality, and background became invisible. Tsui frames this within the broader history of who gets to swim, drawing on historian Jeff Wiltse's Contested Waters to trace how American municipal pools shifted from integrated working-class spaces to racially segregated ones. Desegregation prompted a mass abandonment of public pools by white swimmers and a shift to private pools. The resulting gap persists: Black children drown at five times the rate of white children.

The Competition section traces swimming from ancient military applications through the first modern Olympics in Athens in 1896, where Hungarian Alfréd Hajós won in icy Mediterranean waters. Tsui profiles Charlotte "Eppie" Epstein, who founded the Women's Swimming Association in 1917 and shepherded Gertrude Ederle to her record-breaking 1926 English Channel crossing, which beat the men's record by two hours. She turns to Dara Torres, who competed in five Olympics across nearly 25 years and, at 41, lost the 50-meter freestyle gold in Beijing by one-hundredth of a second. She addresses the psychological toll through Michael Phelps, whose 28 Olympic medals came alongside depression and suicidal thoughts before he found renewed meaning by prioritizing family. Tsui travels to Japan to explore Nihon eiho, the classical swimming martial art practiced by samurai, whose highest principle is mizu no kokoro, "mind like water." She argues that the progression from martial skill to spiritual practice illustrates how swimming encompasses whole personhood.

The Flow section explores swimming as a conduit for creative thought. Tsui introduces psychologist Mihaly Csikszentmihalyi's concept of flow, a state of total immersion in which the self falls away, and argues that entering water offers two kinds of immersion at once. She recounts Lord Byron's 1810 swim across the Hellespont, the four-mile Turkish strait, and cites neurologist Oliver Sacks, who composed books in his head while swimming daily, and open-water swimmer Lynne Cox, who describes a state she calls "sea-dreaming." Tsui reflects on swimming as ritual through her husband's family tradition of crossing Lake George, where his grandparents met on a swimming raft in 1939, and through her reconciliation with her estranged father during a swim together in the South China Sea. She answers her central question by arguing that survival, well-being, community, competition, and flow all run together, shifting with the season and stage of life. She watches her son Felix jump off a diving board for the first time, suspended for one glorious moment before hitting the water.

In the Epilogue, Tsui returns to Chambers, who in May 2018 was diagnosed with Guillain-Barré syndrome, a rare neurological disorder in which the body's immune system attacks the nerves, leaving her paralyzed from the waist down. Five weeks after hospitalization, Chambers returned to San Francisco Bay for a five-minute birthday immersion surrounded by friends. She tells Tsui that her first medical crisis made her a swimmer and she approaches this new ordeal with the same conviction, preparing once again to begin at the water's edge.