The volcanic island of Surtsey, Iceland, was built during the period November 1963 to June 1967 and is one of the few oceanic volcanic islands that has formed and survived in recent times. New stimulus to geologic work on the island was provided in 1979 by completion of a 181-m-deep hole that was drilled to investigate the structure of the volcano and the active hydrothermal system below.

During August 1985 an international group of researchers undertook a series of geologic and biologic investigations on the island. This work was facilitated by new aerial photographs taken by the Icelandic Geodetic Survey and a new bathymetric map of the Surtsy region made by the Icelandic Hydrographic Service (both in Reykjavik). Ground surveying of markers appearing in the photographs will permit a major revision of the to pographic map of the island (scale 1:5000). The new bathymetry defines the extent of continuing erosion of three volcanic vents, two of which formed short-lived islands during the Surtsey eruptive episode. Since 1967, when the first bathymetry of these submarine features was made, the summitt errace of Syrtlingur has been reduced from 23 to 32 m below sea level; that of Jolnir, from 15 to 37 m; and that of Surtla, from 32 t o 46 m.