In this paper, I call for geographers to engage further with a so far under-explored concept of the socio-ecological imagination, which I define as a variant of political-geographical imagination(s) concerned with envisioning (and progressing) the transformation of relationships between human society and the rest of the planetary environment. In response to escalating ecological breakdown, and a recent surge in environmental movement mobilisation(s) led in many places by young people, this paper seeks to contribute to expanding understandings of the socioecological imagination, drawing on interviews and participant observation with young environmental activists in the North East of England. The paper performs two major tasks. First, through analysing the ways in which the environmentalists narrate their imaginaries of socio-ecological transformation(s), it is argued that dominant oppositional tendencies within participant narratives result from a tension between antagonistic and imaginative forms of transformative politics. Second, the paper explores in more depth the main forces constraining the imagination of alternative socio-ecological futures, proposing three major interconnected barriers that emerge from the environmentalists' narratives: crisis lockin; colonisation of the social imaginary; and dualistic temporal imaginaries of transformation. In sum, I suggest that these barriers warn of an imaginative gap between our current social reality and just and sustainable futures, driven by structural and psychological pressures faced by activists in the current era of multidimensional crisis. Bridging this gap can be aided by a greater engagement of geographers and environmental movements with a socio-ecological imagination and a processual understanding of space-time.