The data are the carbon dioxide (CO2) concentrations and partial pressures measured in a Red Sea coastal lagoon seagrass bed and adjacent mudflat, and in a coral reef lagoon. Gases were measured with underwater and autonomous sensors with a frequency of 1 measurement per minute for durations of 8 to 20 days between December 2021 and December 2022. The associated data on salinity, temperature, pressure and O2 concentration interpolated to 1 min interval can be found in doi:10.1594/PANGAEA.948547. The air-sea fluxes of CO2 (FCO2) are given in mmol m-2 min-1, and calculated using the equation k600(CO2)= -0.08+ 0.26v + 0.83u 0.59h from Rosentreter et al., 2017
