There may be something in H.P. Lovecraft's "At the Mountains of Madness" after all.
A massive canyon system and lake have been found running under the ice on the Antarctic continent [cnet.com], according to satellite data. And, if the data is being read correctly, that system runs for over 1,000 kilometres (621 miles) up to depths of 1 kilometre (3,280 feet).
Like the explorers in Lovecraft's 1931 novella [wikipedia.org], which details the fictional discovery of ancient ruins in the Antarctica, a team of researchers is currently working on revealing the full depths of the huge and ancient structure.
The canyon system, located in the difficult-to-map region of Princess Elizabeth Land in East Antarctica, vastly outstrips the Grand Canyon, which measures 446 kilometres (277 miles) in length.