To deepen the understanding of complex relationships in the Wadden Sea ecosystem, the ICBM operates the Spiekeroog Time-Series Station (TSS). This permanent measuring station is located in the sea tidal flat of the Otzumer Balje between the East Frisian islands Langeoog and Spiekeroog (53°45.02' N, 07°40.27' E). The station was established as part of the DFG research group BioGeoChemistry of the Tidal Flat in autumn 2002. The work of the DFG funded research group ended in 2009. Within the COSYNA network (Coastal Observation System for Northern and Arctic Seas) of the HZG (Helmholtz Zentrum Geesthacht, hereon since 2021) the station could be equipped with new technology and sensors and thus the lifetime could be extended. The permanent measuring station lays the foundation for the SCO and is integrated as an important infrastructure in many projects and teaching. The understanding of the interrelationships is crucial to predict the consequences of storm surges or the currently registered sea level rise on the Wadden Sea and to take appropriate coastal protection measures. In this context, the monitoring station is now an indispensable tool for Wadden Sea-related research at ICBM.