This volume contains most of the papers which were presented at the Interdisciplinary Symposium No. 4 "Geodetic Features of the Ocean Surface and their Implications" during the XVIII. General Assembly of the International Union of Geodesy and Geophysics (IUGG) in Hamburg, August 1983. The symposium was jointly sponsored by the International Associ­ ation of Geodesy (lAG) and the International Association for the Physi­ cal Sciences of the Ocean (IAPSO), and was as such one further step in animpQrtant line of international and interdisciplinary symposia, re­ lated to the field of Marine Geodesy. Originally the term "Marine Geodesy" was widely understood as "Geodesy in the Marine Environment" and dealt primarily with two as­ pects: precise position determination at sea and determination of a fine structured marine geoid. However, mainly with the impact of satel­ lite radar altimeter measurements, a new understanding began to develop: it became evident that the field of Marine Geodesy could not be treated adequately from geodesists alone but that it needed close cooperation with related disciplines such as oceanography and marine geophysics. Symposium No. 4 at Hamburg could demonstrate that this cooperation has already become a lively reality. The "geodetic features of the ocean surface" don't only reflect oceanographical but also marine geo­ physical aspects. As such scientists from geodesy, oceanography, marine geology and geophysics came together to present their ideas and to dis­ cuss questions of mutual interest.