The British Geological Survey (BGS) briefing note authored by geoscientist Tim Armitage highlights the critical importance of underground hydrogen storage for the UK's energy transition towards achieving net zero emissions. As renewable energy sources like wind and solar become more prevalent, the need for reliable, long-duration energy storage solutions grows, making hydrogen a promising energy carrier. The briefing identifies salt caverns, lined rock caverns, and depleted hydrocarbon fields as key underground storage technologies that offer scalable and long-duration storage options necessary for a stable renewable-based energy system. Despite the potential, there are significant knowledge gaps and challenges to address in achieving large-scale storage capacities. The briefing outlines recommendations to bridge these gaps, including the need for more demonstration projects, comprehensive integration of hydrogen storage into the UK's energy strategy, and increased research and development investments. While acknowledging the promising role of technology in stabilizing the grid and meeting climate targets, the briefing emphasizes the requirement for significant investments and efforts to overcome technical, regulatory, geological, and commercial obstacles for successful deployment. By addressing challenges such as regulatory clarity and promoting wider adoption, the UK can build necessary capabilities for a reliable hydrogen supply and a sustainable energy future.