Underwood is both a geographical feature of the City of Hollywood, a chasm approximately sixty-seven miles deep, and the district located within it. Three miles across at its widest point, it is visible from space. It was formed during the Big One and is theorized to have been a major fault line. However, due to the reality-altering effects of the Big One, it is unknown if that fault line even existed beforehand. The chasm is deep enough to reach the mantle below, and the seething molten rock provides nearly limitless free geothermal energy to the Hollywood region that is tapped exclusively by the Perdition Power Company and resold at great profit.