A world-wide test program was undertaken by Task Group G 1.09.02.03 to assess the relative corrosivity of seawater at 14 test sites. Aluminum alloy A95086, copper-nickel alloy C70600, and carbon steel alloy KOI501 specimens were prepared at one location, shipped to the various sites, and returned to the original site for final evaluations. Results obtained through three years of testing indicate that average corrosion behavior was generally within limits of previously published results. Individual site characteristics have been identified, however, that can have a profound effect on test results. Even when the ASTM standard test method was prescribed, variations affecting corrosion results became evident. In reality there is no natural seawater environment, as identified to date, in which to test materials. The final five year results are yet to be collected, but the cooperation of all program participants has contributed much toward accomplishment of the objectives. Still, more frequent and broader monitoring of sea-water variables at the exposure sites would assist in interpreting corrosion results.