This paper is in four parts. Part one explores the Blue Pacific, explaining that contemporary regionalism in the Pacific draws from a well-established pan-oceanic identity to negotiate shared challenges. Part two considers the ways that the Pacific Ocean itself is changing in response to a warming climate, with devastating consequences for the security of Pacific island states. It also details the Pacific’s collective diplomacy on climate change. Part three explores the return of geostrategic competition to the Pacific Ocean—as a rising China begins to challenge US sea-power in the western Pacific—and evaluates the response of Pacific island states. The fourth and final section explores Australia’s place in relation to the Blue Pacific and considers tensions between Australia’s strategy of regional integration and the collective diplomacy of Pacific island states.