This data set consists of environmental and geochemical information obtained from samples of 27 sediment cores collected from the vegetated shoreline of three lakes in Finland (Kallavesi, Vesijärvi and Oulujärvi). The sampling campaign occurred in August 2023. For each sediment core, we calculated the sedimentary organic carbon stock (kg/m2). We also measured environmental parameters (water depth, slope, vegetation density and fetch length) that could drive the accumulation of organic carbon in the sediments.