Scientists have discovered what they believe is one of the biggest canyons in the world.
The huge canyon, which is 800km long and around 800m deep, was found beneath the ice sheet that covers most of Greenland, reports the BBC.
Scientists were researching climate change in the area and mapping out Greenland’s bedrock by radar when they made the discovery by mistake.
The British Antarctic Survey described the find as remarkable.
The canyon was carved out by a river more than four million years ago and has never been seen by humans.
It's a continuous canyon. It's pretty deep. It very much looks like it predates the ice sheets,” said lead author, Professor Jonathan Bamber of Bristol University.
“We think it's indicative of a river system that was here before the ice sheet was there, and which perhaps was modified by the ice sheet cover some, but not much.
"It looks like it was a pretty extensive river system millions of years ago.”