Tunnels of Clodagg

Deep underground, with an exit at the canyon, a large burrowing monster known as Clodagg dug a large series of caves into the rocks of the eastern lands. His reign was legendary, as he held all of the lands in fear, striking down wanderers and travelers with mighty swipes of his huge paws. Clodagg was eventually vanquished, but his tunnels remain a hidden source of shelter for anyone who does not wish to be found. This, of course, includes bandits, robbers, and unsavory sorts of characters, who use the massive system to travel the land undetected. The caves are dark, winding and confusing, a maze made of rock and dead trees, and is not the kind of place you'd want to travel to for recreational purposes.