Observator Instruments has recently delivered seven OMC-7012 data buoys. These data buoys will be used to measure the salinity of the water at various points in the Lek, a river in the Netherlands. The buoys have a diameter of 120 cm and are equipped with a Saint Andrew’s cross, a top light and a radar reflector for safety reasons. The salinity is measured by a conductivity and temperature sensor, which is mounted below the waterline. This sensor is connected to an OMC-048 data logger. The OMC-048 has an internal modem, with which the measurement results will be periodically sent to the customer via the 4G network. The configuration of the logger can be adjusted remotely in a web portal. The system is powered by solar panels and a battery.