From offshore border enforcement to detention centers on remote islands, struggles over human smuggling, detention, asylum, and associated policies play out along the geographical margins of the nation-state. In this paper, I argue that islands are part of a broader enforcement archipelago of detention, a tactic of migration control. Island enforcement practices deter, detain, and deflect migrants from the shores of sovereign territory. Islands thus function as key sites of territorial struggle where nation-states use distance, invisibility, and sub-national jurisdictional status (Baldacchino & Milne, 2006) to operationalize Ongs (2006) graduated zones of sovereignty. In sites that introduce ambiguity into migrants legal status, state and non-state actors negotiate and illuminate geopolitical arrangements that structure mobility. This research traces patterns among distant and distinct locations through examination of sovereign and biopolitical powers that haunt asylum-seekers detained on islands. Offshore detention, in turn, fuels spatial strategies employed in onshore detention practices internal to sovereign territory.