Tenuis Cavus is a region within the north polar cap where the underlying surface is visible. Ice comprises the top part of this image captured by NASA 2001 Mars Odyssey spacecraft.
Orbit Number: 61283 Latitude: 84.7719 Longitude: 2.80914 Instrument: VIS Captured: 2015-10-07 19:42
http://photojournal.jpl.nasa.gov/catalog/PIA20112