Pillar Deep is a terraced area located toward the northeast side of the Maelstrom. It has many thermal vents releasing steam and gas bubbles. There are hundreds, perhaps thousands, of enormous stone-like columns stretching toward the surface. They are not columns at all but rather, they are colossal tubeworms, grown to gigantism on the acidic gas from the volcanic fissures. Innumerable smaller worms inhabit this area as well.
It is also the home of tube wyrms.