<p>Low-frequency sea level variability can be a critical factor for several wave energy converter (WEC) systems, for instance linear systems with at a limited stroke length. Consequently, when investigating suitable areas for deployment of those WEC systems, sea level variability should be taken into account. In order to facilitate wave energy developers in finding the most suitable areas for wave energy park installations, this paper describes a study that gives them an additional tool by exploring the annual and monthly variability of the sea level in the Baltic Sea and adjacent seawaters, with focus on the Swedish Exclusive Economic Zone. Over 10 years of reanalysis data from the Copernicus project have been used to conduct this investigation. The results are presented by means of maps showing the maximum range and the standard deviation of the sea level with a horizontal spatial resolution of about 1 km. A case study illustrates how the results can be used by the WEC developers to limit the energy absorption loss of their devices due to sea level variation. Depending on the WEC technology one wants to examine, the results lead to different conclusions. For the Uppsala point absorber L12 and the sea state considered in the case study, the most suitable sites where to deploy WEC parks are found in the Gotland Basins and in the Bothnian Sea, where the energy loss due to mean level variations is negligible.</p>