The tunnel systems in Vietnam were used by the Viet Cong guerillas as hiding spots during combat as well as being used for communication and supply routes, hospitals, food and weapon storage, and living quarters.
Living conditions within the tunnels were harsh. It was difficult to obtain food or water, and there wasn’t a lot of air flow. There were numerous bugs that infested the tunnels, such as ants, poisonous centipedes, spiders, scorpions, and mosquitoes. There were also snakes and bats, although those were harmless. People in the tunnels were also prone to sickness, especially malaria.
Tunnels rats were soldiers ordered to go into the tunnels and kill any remaining soldiers in the tunnels, as well as to plant explosions to destroy the tunnels. They were only armed with .45 caliber pistols and a flashlight. Usually, they were allowed to have a different weapon of their own choosing. Tunnel rats were always small people that would be able to fit into the narrow tunnels.