GEBCO 4th Edition
Sheet A I (N)
Sheet A 'I (S)
Sheet B 'I (S)
Sheet B IV (N)
Sheet B 'IV (S)
Sheet C I (N)
Sheet C 'I (S)
Sheet B I (N)


The Sixth International Hydrographic Conference (1952), saw the need for a new (fourth) edition. Due to a substantial increase in the amount of incoming bathymetric data, the Conference decided on a 5-year cycle for updating the various sheets. Consequently, work on the fourth edition commenced in 1958 before the third had actually been completed. The 2 sheets published in 1958 and 1961 were to be the last to be based on compilations prepared by the IHB.  The continued production of charts incorporating the large volumes of new data was clearly beyond the resources of the Bureau alone and a new organizational structure was sought.

In 1965, an agreement was made between the IHB and the French Institut geographique national (IGN) regarding the production of the remaining sheets of the fourth edition. Under the terms of this agreement, the responsibility for the publication and sales of the GEBCO was taken over by IGN, with the IHB acting as the coordinator for the whole activity.