"It's an exciting day in Aquamarina! The entire community has gathered for the opening of a new playground. But when the equipment falls apart because some of the pieces have vanished, it's up to a mermaid named Violet and her best friend, Wally the narwhal, to solve the mystery of what happened. After the adventure, explore fun facts about ocean science and civil engineering included at the back of the book!"--Provided by publisher.