The Sicily Channel Observatory (SiCO) is a twin-mooring system placed in a key area connecting the Eastern and Western Mediterranean Sea. It is moored at about 500 m depth between Sicily and Tunisia, and performs continuous monitoring of the surface and intermediate exchange of water masses. Equipped with ADCPs, and high precision CTD probes for continuous measurement of hydrological parameters, it has been operative since 1993. Maintenance and data recovery are managed twice per year. Developments towards real time data transmission are planned for both installations. In occasion of the 6-month maintenance, which is done using a fully equipped research vessel, along the transect connecting the edges of the channels, additional measurements are carried out, which will be available to the users on specific request. Those are physical (CTD stations, vessel mounted ADCP, lowered ADCP profiles) and chemical (dissolved oxygen, dissolved inorganic nutrients) measurements. Historical data has been published here.