The East Antarctic Ice Sheet is hiding a very, very big secret.

Geologists studying satellite imagery of the remote Princess Elizabeth Land in East Antarctica, one of the largest unsurveyed land surfaces on Earth, have discovered evidence of a massive subglacial canyon system buried beneath the ice.

Tipped off by the physical hints, the team of researchers utilized radio-echo sounding to pull back the white curtain and peer through the ice. What they found is an absolute monstrosity of geology, a canyon system believed to be more than 685 miles long and as much as 0.6 mile deep. In some places, the measurements failed simply because they were too deep to be recorded. And there's more:

“Linked to the canyons, a large subglacial lake may exist that may be the last remaining large (more then 62 miles in length) subglacial lake to be discovered in Antarctica,” the authors write in a paper published in Geology. It's estimated that this subglacial lake alone may cover as much as 480 square miles.

The geologists believe the canyon system was likely carved out by water. Because it's so ancient, however, it's not clear if it formed before or after it was entombed in ice.

"Discovering a gigantic new chasm that dwarfs the Grand Canyon is a tantalising prospect," study co-author Professor Martin Siegert from the Grantham Institute at Imperial College London told IANS. "Our international collaboration of U.S., U.K., Indian, Australian and Chinese scientists are pushing back the frontiers of discovery on Antarctica like nowhere else on Earth."

Should the initial study's results be verified, the Princess Elizabeth canyon system will take the title of largest ever discovered, dwarfing the Grand Canyon (277 miles) and stealing the crown from Greenland's Grand Canyon (460 miles), itself buried under thick ice. A more comprehensive radio-echo sounding analysis of the remote region is expected to be completed later this year.