Pyhäjärven Callio
Headquartered in Pyhäsalmi, Finland
Callio is a Finnish innovation platform transforming the former Pyhäsalmi mine—Europe’s deepest known base metal mine—into a multidisciplinary underground ecosystem for research, energy, and digital infrastructure. Located in Pyhäjärvi, North Ostrobothnia, Callio repurposes the 1,445-meter-deep mine and surrounding land into a hub for renewable energy projects, data centers, battery storage, pumped hydro, and underground R&D.