The deepest point on land has been found under the Denman Glacier, in East Antarctica.
The canyon has a depth of 3.5km (11,500ft) below sea level.
The important discovery from “BedMachine Antarctica” will help scientists better understand what changes could occur in the polar south region as a result of global warming.
The deepest point on exposed land is currently 413m (1,355ft) below sea level at the shore of the Dead Sea.
A new detailed map from “BedMachine Antarctica” shows the layers of bedrock below the ice sheet and reveals ridges and terrains that could impede and accelerate melting glaciers.
The information will be used in climate models to predict the effect of warming temperatures on Earth.
Dr Mathieu Morlighem, who was part of the team from The University of California, Irvine, who produced the map, told the BBC: “This is undoubtedly the most accurate portrait yet of what lies beneath Antarctica's ice sheet.
He added: "The trenches in the oceans are deeper, but this is the deepest canyon on land," explained Dr Morlighem.
"There have been many attempts to sound the bed of Denman, but every time they flew over the canyon - they couldn't see it in the radar data.”
READ MORE YAHOO UK NEWS HERE:
Dr Morlighem and his team used the law of conservation of mass to create the map after radar instruments had failed to get enough information to create a fuller picture of the region.
The “BedMachine Antarctica” study will be presented at the American Geophysical Union and is also available in the Nature Geoscience journal.