The usage of drifting buoys data to monitor Tropical Cyclones in the SouthWest Indian Ocean Since 1996 and the start of the International Buoy Program for the Indian Ocean (IBPIO) every year an average of about 10 drifting buoys is released before the cyclone season in the tropical waters of the South Indian Ocean. Apart from the oceanographical data they have provided they have significantly increased the amount of meteorological observations -mostly of sea level pressure- over a wide oceanic area where ship observations are fairly scarce. In addition to improve the synoptic analysis of the pressure field within the models they have demonstrated to be useful when monitoring the ITCZ and the cyclogenesis areas. Some of them have been occasionnally visited, more or less closely, by tropical cyclones during their life-cycle thus becoming like passive "hurricane hunters", as providing some ground-truth observations within the cyclones. Although they cannot compare with the enormous amount of data acquired during air recon by the "true" aeronautical hurricane hunters, they have showed their great interest in some occasions however. This poster will present some examples of valuable contribution provided by these drifters in terms of TC track and intensity analysis, notably thanks to a specific oceanographical parameter called "submergence", which can be used as an "eye-detector" when the eye-like central area of light winds is not discernible on satellite imagery.