The Prologue considers the marine space from the perspective of fisheries and biodiversity conservation, examining their legal, environmental, and socio-political dimensions. Over the centuries, the antique, mysterious, and mystic conception of ocean space has been progressively replaced by communities’ and States’ jurisdictions. The modern fishery and ecological visions of the marine space rest on a political-economy representation of space which, through the strong influence of “the West” over the seas and oceans, has gradually become “universal”. The most striking phenomenon since the 17th century has been the growing influence of States on marine and oceanic spaces. The early customary maritime law, and then the recent Law of the Sea, are the political and normative expressions of that historical ocean "appropriation" process. However, the modern evolution of fishery and environmental regulations—particularly through area-based management tools—indicates a new step in the conception of marine space that the Prologue describes as a background to Part I and II. The Prologue is structured around the following themes: (i) Evolution from the antique representation of the ocean space to its modern legal construction; (ii) From gods’ space to human’s space; (iii) Prominence of the modern State in the constitution of marine space; (iv) States’ control of marine spaces by maritime law and the Law of the Sea; and (v) A new page in international management of marine spaces: nature protection, knowledge, and marine protected areas.