I am a physical oceanographer with research interests in high latitude oceanography and sea ice. With technical and scientific colleagues here at the Institute of Ocean Sciences, I have pioneered the application of aircraft-based techniques to the study of ice-covered oceans. Since 1980, we have carried out a wide variety of ocean measurements using such techniques in the Beaufort Sea, the Arctic Ocean and the myriad channels of the Canadian Arctic Archipelago. Recent work has documented temporal variations in the Arctic coastal ocean, over seasonal and longer time scales. We have now records of hydrographic conditions in winter over a 15-year period, and a continuous 7-year record of ocean circulation, ice drift and ice thickness in the southern Beaufort Sea. Our development of reliable techniques for the deployment and recovery of moored instrumentation in ice-covered waters has greatly facilitated the year-round observation of oceanic conditions. The data are providing valuable insights into processes which control the characteristics of the Arctic Ocean: the forcing of the upper ocean by freezing, the ventilation of the Arctic basins, the evolution of pack ice in the thickness distribution of pack ice, and the exchanges of ice and freshwater between the Arctic and temperate oceans. An improving ability to describe the interannual variation in these processes, will facilitate the detection of trends in the Arctic Ocean which may be related to climate variation.