The ocean is the cradle of life. It provides the necessary conditions for the birth of life and reproduction; The ocean is the hometown of the wind and rain, which plays an important role in the regulating and controling the global climate; the ocean is a treasure trove of resources, which provides extremely rich food and huge reserves of a variety of resources to humans ; The ocean is the marine transport hub, which provides the most economical and convenient means of transport for humans'communication across the sea ; the ocean is the modern high-tech research base, which is important areas for the human's exploration of natural mysteries and developing high-tech industries. The main content of the book is about human's return to the ocean, the ocean of material resources, living marine resources.