The notion of the just transition highlights that shifting from fossil fuels to renewable energies should leave no one marginalised, and benefits should be distributed in an equitable and just manner. In this context, a new frontier of resource extractivism is emerging – Deep-Sea Mining (DSM) – which proponents seek to position as a just means of acquiring critical metals and minerals used in renewable energy technologies. Drawing on postcolonial theories of island laboratories, this paper scrutinises DSM and the scramble for minerals by corporations, states, and state groupings. First, through a review of literature, the paper critically examines arguments for DSM that position it as a pathway towards just transition, including through purported benefits to nations in the Pacific Islands Region. Next, drawing on primary data collected during 2023–24 including interviews with Pacific Island climate activists (n = 45), it highlights activist understandings of DSM as perpetuating historic and ongoing colonialism, extractivism, and experimentation in the Pacific Islands Region. Far from a standalone issue, Pacific activists draw on principles of decolonisation and self-determination to engage with the intersecting crises of climate change, extractivism, and to resist DSM. Using DSM as a case study, this paper contends that the plight faced by Pacific Peoples due to the climate crisis, has been weaponised to justice wash extractivism as a climate solution.<p></p>