The Swimmers by Julie Otsuka

From the best-selling, award-winning author of The Buddha in the Attic and When the Emperor Was Divine comes a novel about what happens to a group of obsessed recreational swimmers when a crack appears at the bottom of their local pool. This searing, intimate story of mothers and daughters—and the sorrows of implacable loss—is the most commanding and unforgettable work yet from a modern master.

The swimmers are unknown to one another except through their private routines (slow lane, medium lane, fast lane) and the solace each takes in their morning or afternoon laps. But when a crack appears at the bottom of the pool, they are cast out into an unforgiving world without comfort or relief.
 
One of these swimmers is Alice, who is slowly losing her memory. For Alice, the pool was a final stand against the darkness of her encroaching dementia. Without the fellowship of other swimmers and the routine of her daily laps she is plunged into dislocation and chaos, swept into memories of her childhood and the Japanese American incarceration camp in which she spent the war. Alice’s estranged daughter, reentering her mother’s life too late, witnesses her stark and devastating decline.