This volume serves as a comprehensive visual and descriptive catalog designed to identify and categorize the vast diversity of life inhabiting the world's oceans. Neville Coleman, a renowned underwater photographer and naturalist, utilizes his extensive field experience to document species ranging from simple invertebrates to complex marine mammals. The work provides a structured framework for readers to understand the biological classification and physical characteristics of various marine organisms.

The text is regarded as a practical field reference that prioritizes visual identification and accessible biological summaries for enthusiasts and students alike. Its focus on broad taxonomic breadth makes it a useful introductory resource for those interested in marine biodiversity.