An octopus expert and celebrated artist offer a deep dive to meet the enchanting inhabitants of the world's marine ecosystems. Have you ever walked along the beach and wondered what kind of creatures can be found beneath the waves? Have you pictured what it would be like to see the ocean not from the shore, but from its depths? These questions drive Janet Voight, an expert on mollusks who has explored the seas in the submersible Alivn that can dive some 14,000 feet below the water's surface. In this book, she partners with artist Peggy Macnamara to invite readers to share her undersea journeys of discovery. With accessible scientific description, Voight introduces the animals that inhabit rocky and sandy shores, explains the fragility of coral reefs, and honors the extraordinary creatures that must search for food in the ocean's depths, where light and heat are rare. These fascinating insights are accompanied by Macnamara's stunning watercolors, illuminating these ecosystems and other scenes from Voight's research. Together, they show connections between life at every depth-and warn of the threats these beguiling places and their eccentric denizens face.