The American Library Association has this to say:
Flotsam is a cinematic unfolding of discovery. A vintage camera washed up on the beach provides a young boy with a surprising view of fantastical images from the bottom of the sea. From fish-eye to lens-eye, readers see a frame-by-frame narrative of lush marinescapes ebbing and flowing from the real to the surreal.
“Telling tales through imagery is what storytellers have done through the ages. Wiesner’s wordless tale resonates with visual images that tell his story with clever wit and lively humor,” said Caldecott Medal Committee Chair Janice Del Negro.
The boys have been mesmorized by it. And so have I.