The pressure on coastal seas keeps on increasing (navigation, fisheries, tourism, etc.) and this requires robust observations with adequate coverage. The deployment of wind turbines in shallow waters offers a good example demanding high resolution data in the air column, from the free surface to a height of order 200m. The corresponding structural assessment (loads for fixed towers and loads/motions for floating structures) needs also waves/current/sea level data in the upper part of the water column. To address this challenge a prototype buoy, equipped to measure airflow with a LIDAR and water flow with an acoustic Doppler profiler, has been developed and is here presented. The paper shows the conceptual design and performance of this new buoy as a platform for efficient multi-variable observations. The operation of the buoy is based on batteries and solar cells. The resulting observations have been calibrated with data from an instrumented coastal pier during a pilot deployment off the Badalona coast and a meteo mast off the Dutch coast, covering a number of representative met-ocean events.