A technique was developed for adapting the side-scan sonar to obtain sonar maps of the undersurface of sea ice. The equipment is portable and air-mobile operations were made from single-engine light aircraft. Graphic records displaying the range and relative scattering strengths at 48 kHz were assembled into sonar maps that display the location and shape of under ice features. Data were taken at five sites in the Arctic. The purpose of the research is to develop the underwater technology required to measure the location and shape of features on the bottom of sea ice and to compare the bottom with features on the surface; and to study the scattering of sound from the water-ice interface.