pCO2 is the partial pressure of CO2 in a liquid or gas. In oceanography, it is used to investigate carbon dioxide (CO2) dissolved in the surface layers of the ocean in order to better understand changes in ocean carbon chemistry and ocean acidification due to enhanced atmospheric CO2. The RV Celtic Explorer has a pCO2 Underway System. pCO2 data was collected during the CE18017 (Irish Groundfish Survey) survey on board the RV Celtic Explorer in October/November 2018 by the Marine Institute (MI) in the North East Atlantic Ocean. None