As the demand for space availability in marine environments increases due to the upward trend and intensity of human activities, Marine Spatial Planning (MSP) becomes the key response for accommodating sectoral policies in a way that is both compatible and ecosystem friendly. The book Marine Spatial Planning: Methodologies, Environmental Issues and Current Trends is addressed to people involved in coastal and marine spatial planning and management, such as administrators, planners, decision makers at different political levels, engineers, stakeholders as well as academic staff. It can also provide a sound background to post-graduate and PhD students working in relevant studies. The reader will be able to find information on the legal framework, the methods used so far, the ecosystem oriented approach and the current views as they have been implemented in some marine areas of the world. The book is organized into three sections: Section One focuses on the governance of the seas, international conventions and laws as well as the physical aspects of the marine environment. Section Two includes the most established methodologies in marine environmental quality assessment and planning; particular emphasis has been placed on integrated methodologies merging political, economic, environmental and societal information. Section Three is a selection of case studies that will familiarize the reader on current aspects and experiences gained from marine spatial studies procedures in different areas of the world.