Neddy is an upper-middle-class suburbanite living in the Northeastern United States who views himself as a heroic, masculine figure starting an epic journey. He decides to swim across every pool in the county to reach his home, an eight-mile trek he envisions as an identity-affirming odyssey. He relies heavily on alcohol and maintains a seemingly superficial connection with his community, clinging tightly to his youth and social status.

Lucinda is Neddy's wife, a fellow member of their affluent suburban social set. Though physically absent for most of Neddy's journey, her presence looms over his quest as the namesake of his imaginary river. Like her husband, she adheres strictly to their community's unspoken social hierarchy and frequently declines invitations from those they deem inferior.

The Hallorans are an elderly couple of enormous wealth who are rumored to be Communists. They stand out from their neighbors by embracing relative unconventionality, such as maintaining a large unmanaged wood and a natural pool. They demonstrate genuine, if polite, concern for Neddy's well-being, contrasting with the superficiality of the rest of the neighborhood.

Helen (formerly Halloran) and her husband Eric represent a younger generation in the suburban environment. Eric is one of the few people Neddy genuinely considers a friend. Eric recently underwent a surgery that removed his navel, leaving large scars across his stomach. This physical alteration makes Neddy deeply uncomfortable, as the surgical scars directly contrast with the manicured perfection of their suburban environment.

The Biswangers are a socially ambitious couple who host large neighborhood parties. Grace Biswanger is viewed by Neddy as vulgar and a social climber, mostly because she openly talks about money and attempts to befriend wealthier residents. Despite frequently inviting the Merrills to their gatherings, they are routinely snubbed due to their perceived lower position in the community's rigid social hierarchy.

Shirley is a woman with brass-colored hair who once had an extramarital affair with Neddy. Having moved on from the relationship after he callously ended it, she now views him with a mix of indifference and annoyance. Her pragmatic reaction to his sudden appearance challenges Neddy's sense of entitlement, as she refuses to validate his vanity or yield to his demands.

The Westerhazys are affluent members of Neddy's suburban social set. They host the casual, alcohol-soaked gathering that prompts Neddy to set out on his journey across the county's pools. Like the rest of the neighborhood, they complain of drinking too much the night before.

Mrs. Graham is the owner of the first pool on Neddy's cross-county route. She quickly provides him with alcohol upon his arrival, reinforcing the normalized drinking culture of their community before he slips away to avoid her incoming guests.

The Welchers are neighbors whose property Neddy plans to cross, only to find their home empty and their pool drained. Their sudden absence serves as an unsettling obstacle for Neddy. The discovery sparks his first doubts about the reliability of his memory.

The Clydes reside in the last house before Neddy reaches his own home. By the time Neddy arrives at their property, he is physically exhausted, barely managing to pull himself out of their pool as his strength finally gives way.