Subglacial Lake CECs was previously identified using radar profile data. Subglacial Lake CECs lies beneath 2650 m of ice, close to the Ellsworth Mountains at the divide between the Minnesota Glacier and Rutford and Institute Ice Streams in Antarctica. Four seismic reflection profiles were acquired across the lake to determine water column depth and investigate lake bed properties. Shot gathers with 48 channels and a maximum offset of 500 m were recorded. A seismic refraction experiment was undertaken to determine seismic velocities in the firn. Dual frequency and RTK GPS were used to determine shot locations. Seismic surveys indicate a maximum water depth of 301.3 +/- 1.5 m, at the widest part of the lake, with an estimated lake volume of 2.5 +/- 0.3 km3. Imaging of the ice-lake interface indicates topography with slopes of up to 1.9 degrees. This research was supported by the Natural Environment Research Council, British Antarctic Survey (Polar Science for Planet Earth Programme) and Centro de Estudios Cientificos, Valdivia, Chile.

We present here Bedmap3, the latest suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of Antarctica south of 60degS. Bedmap3 incorporates and adds to all post-1950s datasets previously used for Bedmap1 and Bedmap2, including 84 new aero-geophysical surveys by 15 data providers, an additional 52 million data points and 1.9 million line-kilometres of measurement. This has filled notable gaps in East Antarctica, including the South Pole and Pensacola basin, Dronning Maud Land, Recovery Glacier and Dome Fuji, Princess Elizabeth Land, plus the Antarctic Peninsula, West Antarctic coastlines, and the Transantarctic Mountains. Our new Bedmap3/RINGS grounding line similarly consolidates multiple recent mappings into a single, spatially coherent feature. Combined with updated maps of surface topography, ice shelf thickness, rock outcrops and bathymetry, Bedmap3 reveals in much greater detail the subglacial landscape and distribution of Antarctica's ice, providing new opportunities to interpret continental-scale landscape evolution and to model in detail the past and future evolution of the Antarctic ice sheets. Sponsored by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action group aims to produce a new map and datasets of Antarctic ice thickness and bed topography for the international scientific community. The associated Bedmap datasets are listed here: https://www.bas.ac.uk/project/bedmap/#data