With the launch of SEASAT‐1 in June 1978, an altimeter of improved performance joined GEOS‐3, which had been operational for three years. The advances in design that resulted in <10 cm rms height precision are discussed and some early onorbit performance results presented. In addition to improved resolution and a higher pulse rate, both of which acted to reduce height noise, the SEASAT‐1 altimeter incorporated a microcomputer which allowed flexibility in choice of tracker characteristics and provided for on‐board computation of significant waveheight. Under consideration for future missions are a multi‐beam capability to increase the swath coverage, the primary thrust being more rapid development of current maps, and an uplink programming capability for the microcomputer to facilitate on‐board processing in a way which permits post‐launch algorithm modification. Addition of a rainfall detection mode to the altimeter has also been proposed, and consideration has been given to the reliability improvements needed to support a three‐year mission.