Applications of AVHRR and optical satellite data at the Norwegian Hydrotechnical Laboratory (NHL) include studies of mesoscale eddies in the Norwegian Coastal Current, glacial outflow in fjords, snow hydrology, ice mapping and the motion of polar (atmospheric) lows. Geometrical parameters of mesoscale eddies were gathered from NOAA infrared images for the period 1981-1985 in connection with the study of large surface currents at the Troll Field. An algorithm for computing the phase speed of eddies along the coast was developed in order to estimate the magnitude of the surface currents. In situ, multi-frequency optical measurements in fjords have been tested against multi-frequency Landsat Thematic Mapper images. Surface fjord water laden with glacial till may have a visibility less than 10 cm. Estimates of the amounts of sediments in the surface layer may be made by remote sensing. Flow patterns of the colder melt water in fjords are also revealed by infrared images. A collaboration with the Norwegian Water Resources Board and the Norwegian aerial surveying firm Fjellanger Wideree is in progress to apply AVHRR remote sensing of snow fields to hydrologic models. Ice mapping is performed with data from NOAA, Landsat and SPOT satellites and stereo photogrammetry. NHL has joined several institutions in the U.K. and Canada for this study. Objectives include ice geometries, extent and forecasting. The motion of polar lows is one of the few all-weather applications of AVHRR data at NHL. The work was a joint venture with the Norwegian Meteorologic Institute.