Chasms are deep trenches within the earth. They are a similar element to canyons but may be formed by other means besides river erosion. Like canyons, chasms may form impassable or nearly impassable barriers with a few key traversable locations. They are commonly found within underground cave systems and may be portions of underground cities in fantasy worlds. There may be bridge systems spanning the two sides. There may be steep paths or stairs leading from the bottom to the top. These paths may be secret or hidden.