Marvin, S, . Understanding the socio-technical hybridization of indoor–outdoor relations: Emergent, merged, and stretched. Area. 2021; 00: 1– 10. https://doi.org/10.1111/area.12715Marvin, S, . Understanding the socio-technical hybridization of indoor–outdoor relations: Emergent, merged, and stretched. Area. 2021; 00: 1– 10. https://doi.org/10.1111/area.12715Indoor and outdoor leisure environments are increasingly understood to be mutually constituted through merged relationships, but there has been less focus on the actual forms that hybridization can take. This paper provides an analysis of forms of hybridization through time by focusing on the socio-technical configurations through which three leisure environments are materially constituted. We analyze the key functional elements of these configurations: the technological systems and their genealogies over time that allow the making and unmaking of activities; the spatiality of facilities and systems in terms of their locations and connections across space; and the construction by providers of user pathways between indoor and outdoor activities. The paper uses this structure to compare purpose-built indoor recreational spaces located in the Greater Manchester city region that recreate outdoor activities focusing on skydiving, skiing, and ice wall climbing. We construct a framework of three modes of hybridization—emergent, merged, stretched—that contributes a deeper understanding of the diversity, intensity, and changing temporality of interrelations between indoor and outdoor environments.