Air photographs show that the Otto Glacier in northwestern Ellesmere Island started to surge sometime between 1950 and 1959, with the result that the terminus advanced about 3 km as a floating ice tongue. Maps prepared from the 1959 photographs and from additional photographs taken in 1964 show a further advance of 2-3 km. Information from a subglacial relief map of the terminal part of the glacier, constructed from the results of radio-depth sounding over the glacier in 1966, may have a bearing on the mechanism of glacier surges. Other glaciers in northern Ellesmere Island show features indicative of past surges.