Water samples were collected from Pohjanpitäjänlahti bay in May 2021 from four stations along a coastal salinity gradient. Fluorescence was measured and T-, A-, M- and C-peaks as well as humification, biological and fluorescence indices were calculated from the water samples for characterization of colored dissolved organic matter (CDOM). The samples were collected 8 times straight to plastic bottles from a small boat. The data was collected to a thesis funded by Walter and Andreé de Nottbeck Foundation.