Operational forecasting of open ocean circulation and its biochemical characteristics, requires multi-parameter real-time measurements in the euphotic zone and the upper thermocline. In this paper, we describe the architecture of such a system that was developed for the needs of the Mediterranean Forecasting System. The system incorporates stare of the art sensors for optical and chemical measurements in the upper 100m and physical measurements down to 500m. The sensors can be hosted by independent moorings that communicate via hydro-acoustic modems. The sat- telite data transfer and the large autonomy, allow the operation of the system in any open ocean site. The system will be in pre-operational use from December 1999 until August 2000