This article explores the use of islands as tools of geographical and intellectual containment - or what we call “islanding” - in the scientific and policy literature about gene drive technologies in conservation. In the first part of the article, we explore the narrative of contained gene drive use on islands and discuss how it juggles notions of localness and localization of gene drives and their (test) releases. We question the possibility and narrative of containing the spread of gene drives (...) technologically or geographically, and argue that the gene drives for conservation literature strategically combines contradictory and reductive understandings of islands and containment. The second part of the article is devoted to reflection on nonlocal concerns about gene drives and the possibility of local gene drive decisions. We argue that attempts to legitimize local gene drives through local decision-making evade normative concerns about their nonlocalizability and risk instrumentalizing local communities for nonlocal agendas. Our overarching conceptual aim is therefore to open up a domain of thinking around the possibility of demarcation in our world – of our political, normative decisions, and of our reality – and to argue for the vital importance of reflection on this possibility in technological decision-making. (shrink)