A novel high quality monthly mean sea level (MSL) dataset for 63 tide gauge stations at the german Baltic coastline until 2015. The dataset was generated in the AMSeL_Baltic Sea research project from 2015 to 2018. We generated a new monthly mean sea level datasets from high-resolution sea level measurements and combined these with historic datasets with applied new tidal correction if necessary and if possible with existing monthly MSL time series from the Federal Maritime and Hydrographic Agency of germany (BSH). We averaged the high resolution tide gauge data to monthly values if at least 50 % of data were available each month. Mixing historical measurements with poor or uneven temporal resolution and continuous high resolution observations from modern times can introduce biases in both interannual variability as well as long-term trends of MSL. For this reason we introduced a novel tidal correction for historic data with less than four readings per day.