Carbon capture and storage (CCS) is a way of possibly reducing impacts from fossil fuel emissions by injecting large volumes of carbon dioxide into appropriate geological formations. Some of the existing and proposed storage sites are below the seabed. In order to better understand the environmental impacts of leaks from a sub-surface marine storage facility and to investigate how leaks or potential leaks could be detected, a world-first experiment consisting of an artificial carbon dioxide release from below the seabed was undertaken in 2012. The need for accurate deployments and re-deployments of measurement equipment, the retrieval of biological and sediment samples within very specific areas of the release site and the in-situ measurement of escaping gas volumes, necessitated an extensive scientific diving program. Diving was also employed to determine the most optimum experimental site prior to the program’s initiation and to map the site prior to the beginning of the experiment. Diving also proved to be an essential tool (through observation, photography and videography) in recording the progress of the experiment and the physical interactions and impacts arising from managing a large multi-partner, multi-discipline research program. This is a publication in Diving for Science 2014: Proceedings of the American Academy for Underwater Sciences 33rd Symposium, Martin D.J. Sayer et. al. http://www.aaus.org/uploads/protected/files/publications/symposium_proceedings/diving_for_science_2014.pdf