"An intense, atmospheric novel about the devastating power of friendship, set against the backdrop of two cataclysmic events. When Marissa loses her mother at five, the most intimate relationship of her life begins. Whisked across the globe to Thailand by her oceanographer father, who is determined to channel his grief into completing his wife's research, she meets Arielle, and a fairytale friendship takes hold. During the week, the girls live at the resort owned by Arielle's parents; on the weekends they join the tight community of researchers on a nearby island they are free to explore, discovering the wonders of its reefs and forests. Together they learn to dive, to hold their breath for minutes at a time, as effortlessly synchronized as the manta rays they come to know by name. Together they learn to swim their way out of danger. But then comes a wave Arielle can't outstrip, bringing Marissa a gutting loss. Years later, Marissa, is back in New York, adrift and haunted by the memory of her friend. Over the course of a single, fateful day, as another cataclysm approaches the oblivious city, she revisits her past and, as memory washes over her, discovers how to sustain herself in a fragile world"-- Provided by publisher.