Geisel Honor–winning Yoon's picture-book favorite Penguin meets Ollie the octopus while on an underwater treasure hunt.Penguin takes an undersea dive to explore the ocean floor, looking for riches. After spotting Penguin, Ollie the octopus quietly tails him until the two meet in a cloud of black ink. Eventually, Penguin tracks down the treasure chest and realizes that his friendship with Ollie is the real prize. Yoon's darling little Penguin and signature illustrations rank high in kid appeal. Thick black outlines set each character off from the background. The book offers a playful mashup of realistic details (like Ollie's ink) and more whimsical ones; readers expecting a realistic marine story should look elsewhere. Penguin once again wears his familiar orange scarf, a shark and several jellyfish end up bejeweled (the shark even sports a gold tooth!) after the valuables are discovered, and Ollie puts found knitting needles to good use in an effort to coordinate accessories with Penguin. The final pages include a seek-and-find guide. The moral of the story is a familiar and predictable one, but in this absolutely adorable package, it's sweet and sure to be a hit for fans of the series. (This book was reviewed digitally.)Well-trod territory but a gem nevertheless. (Picture book. 3-5)

PreS-Gr 2— Penguin returns in another adventure! Deep beneath the sea, he sets out to explore the ocean floor for sunken treasure. Searching a hollow log, dark cave, and a kelp forest with no luck, his friend Crab suggests exploring a nearby sunken ship. Suddenly, a black cloud envelopes Penguin and from it emerges Ollie the octopus. Embarrassed, Ollie confesses that too much excitement or nervousness causes him to ink, and he loses his ability to camouflage with his surroundings. Ollie lists the many things he uses camouflage to hide from, like krill, pufferfish, lobsters, and especially sharks. Penguin and Ollie become fast friends and continue the treasure hunt, but when Penguin's friend Shark appears, Ollie disappears without a trace. Penguin and his friends call for Ollie, but he is nowhere to be found. How will Penguin be able to find his new eight-armed friend and the treasure now? In Yoon's familiar style, vibrant illustrations are outlined in black and pair seamlessly with large, clear lines of text, producing a crisp presentation. The last pages offer a scavenger hunt, depicting ocean animals and toys to spot, sending readers flipping back through the pages. Be ready to supplement with nonfiction texts for a deep dive on the octopus, as young readers' interests may be piqued by Ollie's curious characteristics and bubble with questions about ink clouds and camouflage. VERDICT Libraries will want to add Penguin's latest underwater adventure to this growing collection of stories by Yoon.— Emily Brush