The authors provide more than just a superficial descriptive tour of the oceans. The text delves into studying the ocean as an ecosystem or subsets of it, as ecosystems in their own right. The food chain provides one way of understanding an ecosystem, and the adaptations that various creatures have for the niches they occupy. Here, the authors start from first principles, with the photosynthetic species and the depths which they occupy.The book also shows that at the ocean bottoms, even with no photosynthesis, there is still a rich environment for benthic species.The diagrams are well done and readily understandable. The biochemistry is pretty simple, but this is just an introductory text.