Predicted sea level rise caused by anthropogenic climate change threatens to drastically alter coastlines around the world. In the case of low-lying atoll states, it threatens to expunge them from the map. This potential scenario has engendered considerable discussion concerning the fate of climate refugees. Relatively little attention, however, has been given to the impact of sea level rise on existing maritime zones and how these zones, and the resources they represent, might continue to benefit displaced communities. This article builds on the small body of legal scholarship that has taken this matter seriously, to provide a normative analysis, based on principles of global justice, of the best ways of responding to the plight of atoll states. The article thus both extends legal scholarship by applying the principles of global justice to the problem of maritime boundaries, and contributes to the literature on global justice by investigating a salient but hitherto neglected case.