The primary technological objective of the ESEAS-RI project is to support the ESEAS research infrastructure and to facilitate the transnational coordination, the upgrading of the network of observing sites and the standardisation of the network, the operational routines, the databases and the quality-control. in the as a prerequisite for a full scientific exploitation of the present and future sea level observations. The primary scientific objective of the project is to study sea level variations at inter-annual to century time scales and to quantify potential future changes in mean sea level. In order to reach the objective, the following main steps are necessary: 1.Quality control of the hourly tide gauge data accessible through the ESEAS. 2.Determination of vertical land movements at tide gauges in order to decontaminate the relative sea level records for this bias. 3.Determination of sea level variations on inter-decadal time scales in the North Atlantic and the semi-enclosed European seas as well as assessment of secular relative sea level trends for the European coasts. 4.Improvement of the network of ESEAS Observing Sites through upgrading of selected tide gauges and co-location of gauges with continuous GPS. Expected impacts: The availability of a quality-controlled database of hourly tide gauge data, and the successful upgrading of the ESEAS network are major milestones. The project is expected to result in an major improvement of the research infrastructure comprised in the ESEAS. The research carried out in the project will result in an empirical model of sea level variations, which provides a unique basis for future studies of climate processes at decadal to inter-decadal time scales, particularly the North Atlantic Oscillation, as well as a coherent description of the occurrence of extreme sea levels.