The socially just distribution of maritime spaces and their resources among States is a key concern of the 1982 un Convention on the Law of the Sea. This concern underlies the general apportionment of those spaces to coastal States as well as the concrete delimitation of any overlapping claims. The Convention prescribes that such delimitation be equitable. Much attention so far has been given to the judicial performance of such maritime boundary delimitation. This paper focuses on the alternative of delimitation by negotiated agreement of States. It conceives of delimitation as institutionalized oceans governance. This governance seeks to achieve the indeterminate objective of equitable delimitation by combining two broad approaches with machinery for their concretization. For one, the Convention adopts a geographical approach, implemented through the concept of maritime zones extending seawards of the land. Yet the Convention also countenances a non-geographical approach based on historic titles grounded in customary law. For concretising these broad approaches into principles, rules, and decisions, the Convention institutionalizes comprehensive judicial decision-making. Courts and tribunals have indeed developed an acquis judiciaire favouring delimitation by means of the equidistance/relevant circumstances method that is binding on States. However, the Convention gives preference to the equally institutionalized negotiated delimitation of marine entitlements, by means of the agreement of the coastal States concerned. These States therefore retain a considerable margin of appreciation for negotiated delimitation, drawing on state practice to identify the principles appropriate for the individual instance. The paper first develops this governance framework and then exemplifies its workings in the case of the South China Sea, marked by several, ongoing maritime delimitation disputes to be resolved by negotiated settlement.