This proposal addresses the need to spread excellence and widen participation across the European Union by the twinning of research institutions. We propose to twin the Croatian Geological Survey (HGI-CGS) with two world-leading geoscience research institutes, the Geological Survey of Denmark and Greenland (GEUS) and the British Geological Survey of the United Kingdom Research and Innovation (BGS-UKRI), to significantly strengthen HGI-CGS’s research, and in a number of areas transform its capability. The overarching objective is: to deliver a coordinated and targeted programme of training, knowledge exchange and collaboration, involving world-leading experts, to embed cutting-edge research techniques, tools and knowledge within HGI-CGS, leading to a significant and measurable improvement in their geoscientific research capability. HGI-CGS will benefit from a range of research tools, technologies, software and methods at the disposal of GEUS and BGS-UKRI. However, central to this project is the development of active collaboration and partnership between people; between talented scientists within HGI-CGS and highly productive scientists within BGS-UKRI and GEUS, who in a number of cases are world-leading experts in their field. Through close collaboration of scientists working on a range of geoscience topics, facilitated through scientific workshops, two-way scientific exchanges and bespoke training programmes, the project will support HGI-CGS to strengthen research in four important geoscience subject areas, which are at the core of most world-leading geological surveys and geological research institutes: (i) 3D geological surveying and modelling; (ii) groundwater flow and contaminant transport modelling; (iii) geological hazards; (iv) geothermal energy. The project will also enhance research and innovation related to environmental issues: a shift to a low-carbon economy, climate change adaptation and risk management, environmental protection and resource efficiency.