Despite a decades long push to develop what is seen as the vast untapped hydropower potential of the Indian Himalayas, hydropower capacity addition has been delayed and become increasingly expensive in India. Policy documents cite “poor” geology as a major reason for these delays. As hydropower in the form of run-of-river projects expand into the Himalayas, their construction activities encounter poor geology more frequently. This paper analyses hydropower development as an assemblage and examines how risk, especially geological risk, is negotiated to allow hydropower development to continue in the Indian Himalayas. We show how the category of “geological surprises” emerges as an institutional response to the problems of run-of-river based hydropower development in a seismically vulnerable landscape. We further show how “geological surprises” act as a boundary object between hydropower policy, project development, infrastructural finance, and hydropower knowledge, allowing for cooperation and negotiation, to allow hydropower development to continue in the geologically complex Himalayas.