Images obtained by a synthetic aperature radar on SEASAT have been used to measure sea ice displacements over a three day interval in October 1978. The position of a natural ice feature was measured on 5 October and again on October 8; the difference in these two positions is a displacement. The displacement of many features was measured. The tracked features lie roughly along a line and are quite dense-about 2 km apart-over a distance of 865 km. The displacements are about 20 km. Displacement errors grow with distance from shore becoming as large as 3 km. The graph of displacement versus distance has occasional discontinuities of several kilometers. Displacement discontinuities are accurate to ¿0.07 km along track and 3% of their magnitude across track.