Grand Canyon (Greenland)
The Grand Canyon of Greenland is a tentative canyon of record length discovered underneath the Greenland ice sheet as reported in the journal Science on 30 August 2013 (submitted 29 April 2013), by scientists from the University of Bristol led by Jonathan Bamber, University of Calgary, and University of Urbino, who described it as a mega-canyon. Ice-penetrating radar data collected during NASA's Operation IceBridge showed a huge subglacial canyon running from the central region of the island northward into the Arctic Ocean, to the fjord of the Petermann Glacier.