This book gathers the peer-reviewed proceedings of the 1st congress on Geoethics & Groundwater Management (GEOETH&GWM'20), held in Porto, Portugal, in an online format on 18-22 May 2020. Hosted in School of Engineering (ISEP), Polytechnic of Porto based on Porto city (a UNESCO World Heritage Site), the international conference focused on what has now been dubbed “hydrogeoethics”, a novel transdisciplinary, scientific field integrating all dimensions of geoethics in groundwater science and practice. Given its scope, the book is of interest to all researchers and practitioners in the geosciences, hydrology, water resources, hydrogeology, natural resources management, environment, engineering, law, sociology, education, philosophy, culture, among others. This joint congress is the result of a collaborative agreement between the IAH (International Association of Hydrogeologists) and IAPG (International Association for Promoting Geoethics) and reflects the need for concerted actions to achieve sustainable development. The diversity, scale, significance and increasing magnitude of anthropogenic interactions with aquifers and groundwater, which often involve conflicting values or interests, call for analysis, discussions and decisions on the part of the agents involved, e.g. groundwater scientists, policymakers, managers, organisations, professionals and citizens. This approach calls for a responsible, sustainable and human approach to groundwater use and management. The groundwater community involved in the exploration and exploitation, use and management of this increasingly vital natural resource is becoming more and more aware that ethical issues pervade all our attitudes from concept to action and need to be addressed. Diverse values and cultures, science and education, law and policies, human and natural environments and the public and the economic sectors view groundwater and its value and/or role differently. The authors believe that in a globalised and interconnected world, common ground must be found in the interest of peace, human development and sustainability. The main topics covered here include: 1. Fundamentals of hydrogeoethics: cultures, principles and geoethical values on groundwater science and engineering 2. Lessons for a resilient and sustainable future with hydrogeoethics: case studies of geoethics in groundwater science-engineering, profession, and management 3. Scientific and humanistic components of hydrogeoethics in groundwater education and professional training 4. Socio-hydrogeology and ethical groundwater management 5. Geoethics of decision making under uncertainty and ethical issues in neglecting groundwater functioning 6. Groundwater: geological, legal, social, and ethical challenges of a unique natural resource