Under the Ocean introduces young children to the creatures that live in the seas around New Zealand. The book describes different habitats: underwater reefs, the sea floor, the open ocean and the deep ocean. Animals featured in the fact pages include octopus and squid, sharks and rays, whales, dolphins, penguins and many others. Under the Ocean is the third volume in the Explore and Discover series, following Gillian Candler and Ned Barraud's best-selling At the Beach, which was a finalist in the non-fiction section of the New Zealand Post Children's Book Awards, and the popular title In the Garden. Under the Ocean was written in response to children's requests to have a book that included sea creatures such as sharks, octopus and giant squid. Although children can't explore the sea first hand in the way they can explore a garden or the beach, they are fascinated by the amazing creatures that live in the ocean.