This article offers a critical and reflective examination of the impact of the enforced 2020/21 COVID-19 lockdown on ethnographic fieldwork conducted with UK-based young environmental activists. A matrix of researcher and activist challenges and opportunities has been co-created with young environmental activists using an emergent research design, incorporating a phased and intensive iterative process using online ethnography and online qualitative interviews. The article focuses on reflections emerging from the process of co-designing and then use of this matrix in practice. It offers an evidence base which others researching hard-to-reach youth populations may themselves deploy when negotiating face-to-face fieldwork approval at their own academic institutions. The pandemic and its associated control regimes, such as lockdown and social distancing measures, will have lasting effects for both activism and researchers. The methodological reflections we offer in this article have the potential to contribute to the learning of social science researchers with respect to how best to respond when carrying out online fieldwork in such contexts—particularly, but not only, with young activists.