The Oceans Become Global

Aspects of ocean governance have ancient roots, including early anti-piracy campaigns and basic rules for maritime commerce. Sovereign rulers periodically attempted to control ocean space but usually lacked the means to do so. As Spain and Portugal mastered the art of long-range seafaring in the 15th century, however, they attempted to divide the world’s oceans between them, an effort that still stands as one of the most ambitious attempts to divide up the oceans. During that period, Portugal tried to exclude outsiders from the Indian Ocean and asserted the right to control all shipping in the area. Portuguese claims prompted objections from other European powers and set the stage for the Dutch lawyer Hugo Grotius to articulate the doctrine of a “free sea,” based on what he saw as the inherent nature of the oceans. While it faced several rebuttals, Grotius’s conception of the oceans mostly prevailed.