When we are confronted with the loss of someone we love, grief can suddenly hold all the other aspects of life at arm’s length. Left unchecked, what may appear at first to be a slight remove can grow into a deep chasm of despair and sadness. Or maybe an ocean.

In “El Niño,” by Pam Muñoz Ryan (a two-time Pura Belpré medalist and last year’s recipient of the American Library Association’s Children’s Literature Legacy Award), 13-year-old Kai Sosa, a talented athlete, is trying to return to competition on an elite swim team two years after his beloved older sister, Cali, vanished at sea while surfing near their home in Southern California.

Cali, a record-breaking high school phenom, had always been Kai’s North Star, and swimming was their shared passion. With many questions about her disappearance still unanswered, Kai is doing his best to carry the family torch. But he’s plagued by self-doubt, wondering if he even belongs in the water anymore.

Kai’s father, who was an accomplished college swimmer and spent countless hours helping Cali with her training, steers clear of the pool now; his mother, a marine veterinarian at the local aquarium, worries that her son hasn’t processed his grief. Only his little sister, Abby, seems to want to talk about Cali — they both see her in their dreams.

Strange things start happening in their waking life once the two younger siblings find an overdue library book that Cali checked out six times. It tells the myth of Califia, one of an ancestral line of 12 warrior queens tasked with ruling an island of great riches named California.

The Queen Califia of the story discovers that her island is sinking, and saves her people by transmuting them into merfolk, capable of moving between land and sea. Even underwater, though, Queen Califia’s realm is vulnerable to outside forces that threaten its most valuable treasure: a library that holds the world’s sorrow and suffering.

The first time Kai goes surfing after reading the book, dolphins appear around him, including one with distinct moon-like markings who seems to want to tell him something. A pair of gold cuffs described in the story have an eerie parallel in two bracelets Cali inherited from their great-great-aunt Califia, her namesake.

During swim practice, the new coaches, Dominie and Xosé, focus on Kai with unusual intensity, to the annoyance of his teammates. Oddly, practice includes lectures on undersea topography and dolphin communication. One afternoon, Kai overhears Dominie cryptically describe him as “the heir apparent” who “doesn’t have a clue what we’re up against.”

What does this mean? Did Cali believe she was descended from Queen Califia? Does she need Kai’s help? Where has she gone, and is she really gone?

An inventive, absorbing novel that blends elements of magical realism, climate fiction and coming-of-age sports tales, “El Niño” features drawings by the Pura Belpré honoree Joe Cepeda, who also created the cover art for Ryan’s historical novel “Esperanza Rising.”

I love how the chapters are interspersed with passages from the library book about Califia, and how Ryan takes inspiration from existing origin stories about California to establish a rich, complex world of her own.

It’s a world that makes space for feelings — especially sad, difficult ones — and holds them in precious regard.