In this study of the North Greenland ice sheet, we have used digital elevation models to investigate the topographic signatures of a large ice flow feature discovered in 1993 and a unique surface anomaly which we believe has not been observed previously. The small scale topography of the flow feature is revealed in striking detail in a high-pass filtered elevation model. Furthermore, ice penetrating radar show that the sub-stream bed is rough with undulation amplitude increasing downstream. The new feature consists of two large depressions in the ice sheet connected by a long curving trench. The low driving stresses in the region and the increased power of radio echo from the ice/bed interface over the feature clearly show presence of basal water. The shape of one of the two depressions and its location above a bedrock trough is indicative of a sub-glacial lake but we also see evidence suggesting that water transport through a basal hydrological system may be occurring. ¿ 1998 American Geophysical Union