The International Symposium on Marine Positioning (INSMAP) was conceived by the Marine Geodesy Committee at OCEANS 84, Washington, DC. It became clear at that time, that timing is appropriate to focus attention on individual specific problem areas under the broad umbrella of Marine Geodesy. After scheduling INSMAP 86 by the Marine Technology Society, we were fortunate to generate strong support from our co-sponsor s. All their assis tance and support are gra tefully acknowledged. Our special thanks are expressed to the U.S. Geological Survey; Charting and Geodetic Services, NOS/NOAA; Office of Naval Research, and Naval Ocean Research and Development Activity for their support through financial grants (ONR No. N00014-86-G-0107, NOS/NOAA No. 40AANC601637, and USGS No. 14-08-0001-G1207) as par tial funding to the INS MAP 86. We are al so gra teful to the U.S. Geological Survey for providing the auditorium and other logistic support in making the symposium a success. A total of 165 persons attended INSMAP 86, of which 20 percent were from outside the United States. Nine technical sessions and five special workshops were held wi thin a four-day forma t. Invited speakers included Dr. Alan Berman, Dean, Rosensteil School of Marine and Atmospheric Sciences; RADM J. R. Seeshol tz, Oceanographer of the U.S. Navy; RADM John D. Bossler, Director of Charting and Geodetic Services, NOS/NOAA; Mr. Chris von Al t, Woods Hole Oceanographic Institute; and RADM L. H. van Opstal, Hydrographer of the Royal Dutch Navy.