One of us—Alice, a retired lab technician now in the early stages of dementia—comes here because she always has. And even though she may not remember the combination to her locker or where she put her towel, the moment she slips into the water she knows what to do. Her stroke is long and fluid, her kick is strong, her mind clear. “Up there,” she says, “I’m just another little old lady. But down here, at the pool, I’m myself.”

