The SmartBay Observatory in Galway Bay is an important contribution by Ireland to the growing global network of real-time data capture systems deployed within the ocean. Installed on the seafloor 1.5km off the coast of Spiddal, the observatory uses cameras, probes and sensors to permit continuous and remote live underwater monitoring. Data relating to the marine environment at the site is transferred in real-time from the SmartBay Observatory through a fibre optic telecommunications cable to the Marine Institute headquarters and then made publicly available on the internet. A CONTROS HydroC CO2 sensor is installed on the observatory infrastructure. This dataset comprises of the measurements taken from the sensor, which measures the partial pressure of CO2 in the seawater. Suggested Citation: Marine Institute. (2026) SmartBay Observatory pCO2 Data (Processed) [Data set]. Marine Institute, Ireland. doi: https://doi.org/10.20393/A5525C18-36F2-4E7D-891A-C498C9B811CD