This book provides an introduction to ocean sciences that is engaging, evocative and accessible to non-experts interested in marine geoscience, while sparking readers’ interest in important unsolved mysteries in marine science. The scope of the book is quite broad, but focuses on the physical ocean and its geological evolution, including the author’s experiences working as an oceanographer over the last thirty years. Across ten chapters, the book traces the origins of the ocean from its formation 4 billion years ago, reviews the discoveries of the theory of plate tectonics, the ice ages and the great ocean conveyor, and discusses seafloor features (canyons, seamounts, trenches, abyssal plains, etc.), how they formed and their current environmental issues. The book concludes with a prognosis for the future ocean we might expect with global climate change and other human impacts.