There's a whole lot about our own planet that we've not yet explored. After years of data, scientists have announced the discovery of a 460 mile long canyon underneath Greenland's ice sheet. It's longer than the Grand Canyon, and no human has ever laid eyes on it before.

The canyon is hidden by a thick layer of ice, and the half mile deep canyon was discovered by an ice penetrating radar. According to Jonathan Bamber, professor of physical geography at the University of Bristol:
One might assume that the landscape of the Earth has been fully explored and mapped. Our research shows there's still a lot left to discover.
Scientists were able to send out radio waves that would travel through the ice, bounce off the bedrock underneath, and come all the way back up. Meaning the longer a radiowave takes to come barreling back, the deeper that particular bit of canyon is.