A terrain analysis technique relating ice-surface plan curvature to basal topography is applied to the Antarctic Ice Sheet. The technique suggests complex bed topography and a large subglacial basin more than 1500 m below present day sea level under the Recovery Glacier and its catchment in East Antarctica. Despite the importance of accurate subglacial topography for understanding the nature of ice flow and for numerical modeling, available data in this region are sparse. The presence of a large area of ice grounded below sea level, flowing at elevated velocities could have significant implications for the potential stability of this region of East Antarctica, previously thought to contain only small areas of marine ice sheet. The catchment region alone contains an ice volume equivalent to 2.6 m of global sea level rise, therefore it is important that the nature of the basal conditions in this region are better understood.