The book is conceived at two levels. An introductory one intended for undergraduate and/or environmental studies students and the other (in the appendix) for advanced students (graduate). The book is different from others on the same subject which are either too descriptive or too much specialized. Beside there are large sections on biogeochemistry not usually found in other textbooks. Whenever possible an approach based on entropy considerations is introduced. The book includes a quite classical introduction to the thermodynamics of ocean and atmosphere, then the circulation of the ocean and atmosphere, the connection climate-chemistry with main emphasis on the carbon dioxide problem. The chemistry is also considered in connection with the polluted atmosphere and ocean and particulate in the atmosphere . A chapter is dedicated to the biogeochemical cycles which are solved both with the integration of a system of equations or matrix algebra. An original chapter is dedicated to sea-atmosphere interactions which includes the monsoons meteorology, hurricanes and the ENSO phenomena. Finally a concise description of the fluid environments in the Solar System is given.