Differentiating microbial, anthropogenic, and thermogenic sources of carbon dioxide (CO₂) and methane (CH₄) in background air is an important element of understanding
upper ocean ecosystem processes. Here we present isotopic data of carbon dioxide and methane from the Fleur de Passion sailing research vessel which traveled from Dakar (Senegal) to Carbo Verde, the Azores, and to France between April and October 2019 as part of the larger Ocean Mapping Expedition by the Geneva based NPO Fondation Pacifique.