1958. Besides the recording of mean sea level, the modern tide gauge station will also provide precise meteorological data and permanent GPS observations. This makes it possible to permanently monitor the position of the GPS antenna to determine the position of the reference point of the tide gauge station, and it allows us to connect the monitoring of the sea level with the terrestrial reference system. The paper presents geodetic activities at the tide gauge station Koper during the test period, carried out in order to monitor the local stability of the GPS antenna within the terrestrial micro network.