The book is devoted to the history of the study of deep-sea bottom fauna from the beginning of the 19th century to the present day. The presentation of the facts of this story is accompanied by a story about technical achievements that allowed scientists to lift marine animals to the decks of research vessels or observe them through the windows of inhabited underwater vehicles at maximum depths of the World Ocean up to 11 kilometers. The book is designed for a wide range of readers, but first of all the author thought about a 12-14-year-old teenager, for whom this book may be the first on the problem that interested him and who, after reading it, wants to expand his knowledge; about a student seeking to form an opinion on deep-sea bio-oceanology; about the scientist and the sailor of the scientific and commercial fleets who are interested in the work of their colleagues in the relatively recent past, as well as about those who love the sea, the romance of its secrets and the excitement of their discoveries.