The Anthropocene is an era in which humans have become the primary driver of planetary systems, not least the global hydrological cycle. This is posing significant challenges for managing the globe's water resources, and is catalyzing a shift in the focus of water law, governance and policy research. One important feature of this shift is a burgeoning focus on groundwater resources and their exploitation, particularly in developing countries. As surface water succumbs to climate pressures, groundwater use has increased rapidly as a source of food production and economic development. A fundamental question for modern water law and governance research is: what are the key challenges and opportunities for effective design and implementation of groundwater law to achieve sustainable and inclusive development. This article provides insights into this question through an empirical examination of Costa Rica. Drawing on an empirical analysis of 40 semi-structured interviews with public and private stakeholders in Costa Rica, the findings identify the following challenges and opportunities for groundwater governance: (i) recognition of water as a public good and clear ownership; (ii) insufficient definition of groundwater and embedding within the concepts of sustainable and inclusive development and participation; (iii) inadequate organization and toolbox, including implementation.