AbstractFerryBox systems are newly developed instrument for automatic measurements of a series of environmental oceanographic parameters to support monitoring of the water quality of coastal and offshore waters. The principal idea of the FerryBox is to use ships of opportunity like ferries or other commercial ships on fixed routes to make high-frequent repeated automatic measurements of important oceanographic parameters. Measurements are made in a flow-through system where different sensors are applied to measure continuously different parameters. The sustainability of the systems for long-term unattended measurement can be enhanced by using automatic cleaning systems so that maintenance can be significantly reduced. Basic FerryBox systems are equipped with sensors for measuring seawater temperature, salinity, turbidity, and chlorophyll-a fluorescence as a measure of the amount of algae. The systems can be extended with other sensors for e.g. the carbon cycle (pH, pCO2, alkalinity), algal composition as well as nutrients like phosphate, nitrate and silicate. After an initial impulse by an European funded project FerryBox systems are more and more used by different European agencies as well as research institutes.