The formation of tunnel valleys and other subglacial erosional landforms is among the deepest-reaching erosional processes. Such deep erosion during potential future ice ages could seriously affect the integrity of the geological barrier of a radioactive waste repository. To address the topic of subglacial erosion and its relevance for the long-term safety of radioactive waste repositories, a 2 d virtual workshop was organized by BGR (Federal Institute for Geosciences and Natural Resources) and BGE (Federal Company for Radioactive Waste Disposal) in December 2021. As a follow-up, this special issue aims to collect studies on all aspects of subglacial erosion and its treatment with regard to site selection and the long-term safety of radioactive waste repositories.