The Great Hollow is not the Big Hole despite the similar name.
The Great Hollow is an enormous cavern that serves as the home of the Lizard Clan, one of the Grassland's Six Clans. Glowing minerals are embedded in the rocks forming the cavern and this, along with the flickering blue flames present there, gives the location an air of mystery. The Great Hollow is known for it's massive size, housing the Karaya Clan following the destruction of their village. The Fire Bringer also temporarily take refuge there after being defeated by the Harmonian Army near the Duck Village.
Additional caves and tunnels spread out from the Great Hollow in a circular formation. Item shops and inns are also available here.