This dataset includes measured data over the epi-mesopelagic layer (0-800 m depth) of 27 stations with 14 of them inside or in the vicinity of a cyclonic eddy that formed off Mauritania along the ∼ 900 km zonal corridor between Mauritania and the Cabo Verde islands in the eastern Tropical North Atlantic during the M156 cruise on the RV Meteor from July 3rd to August 1st 2019. Chromophoric and fluorescent dissolved organic matter were measured with a Shimadzu® 1800 UV−VIS double beam spectrophotometer and a Cary Eclipse Fluorescence Spectrophotometer respectively. The data included the absorption coefficient at 325 nm (a325) and the four fluorescent components obtained from PARAFAC analysis.