SEASAT's ability to measure surface wind and wave fields over the area of the Joint Air-Sea Interaction experiment (JASIN) by means of its radar altimeter, microwave radiometer, scatterometer and synthetic aperture radar (SAR) has been analysed over some eight passes selected to provide a variety of surface conditions from light winds (4m/s) to moderately strong winds (16-20m/s). Comparisons were made not only with observations from research vessels and buoys but also between one SEASAT sensor and another. It is concluded that a description as accurate as surface observations but with considerably better resolution was achieved.