The Underhive is a vast, sprawling network of tunnels and ruins located beneath the city of Necromunda. It serves as a dangerous habitat for various factions, including gangs and scavengers, who fight for survival and resources in its dark, polluted environment. The Underhive is characterized by its industrial decay, toxic waste, and makeshift settlements. Life in the Underhive is harsh, with constant threats from rival gangs and mutated creatures. The area is rich in valuable materials, attracting those willing to take risks. The struggle for power and territory defines the culture of the Underhive, making it a central element in the lore of the Warhammer 40,000 universe.