This article shows how wildlife and marine conservation in Tanzania lead to forms of ‘green’ or ‘blue grabbing’. Dispossession of local people's land and resources has been gradual and piecemeal in some cases, while it involved violence in other cases. It does not primarily take the usual form of privatization of land. The spaces involved are still formally state or village land. It is rather the benefits from the land and natural resources that contribute to capital accumulation by more powerful actors (rent-seeking state officials, transnational conservation organizations, tourism companies, and the State Treasury). In both cases, restrictions on local resource use are justified by degradation narratives, while financial benefits from tourism are drained from local communities within a system lacking in transparent information sharing. Contrary to other forms of primitive accumulation, this dispossession is not primarily for wage labour or linked to creation of a labour reserve. It is the wide-open spaces without its users that are valued by conservation organizations and the tourism industry. The introduction of ‘community-based conservation’ worked as a key mechanism for accumulation by dispossession allowing conservation a foothold in village lands. This foothold produced the conditions under which subsequent dispossessions could take place.