Islands are closely linked to globalized material flows, with specific constraints and vulnerabilities. Counter-intuitively, they are not examples of metabolic loops of consumption, production and waste. We argue that islands are key territories for better understanding the consequences of flow in terms of vulnerabilities, colonialism and externalization, precisely because of the way they are connected (rather than isolated) to globalized material flows. This research is an interdisciplinary material and geographical analysis of waste realities in two French/formerly French island territories (Manglou et al., 2022; Bahers et al., 2022): the Comoros and New Caledonia. It draws on metabolic analysis and waste studies to address the different perspectives that these approaches open up for the study of island territories. An analysis of material flows (EW-MFA method with a spatialization of flows) allows us to sketch out metabolic profiles that show the contribution of the dominant mining and agricultural industries to waste production. This flow approach is combined with a social geography approach. The socio-political context of each island is used to explain contemporary resource and waste management policies and practices.