Pipes are a location of long linear or interconnected pipework. Fictional pipes are often large enough for people to walk on or through, allowing characters access to new areas or the ability to sneak into locations. Large pipes may also transport useful liquid material (a chance to insert a fictional material) from a source to a refinery. They may be a type of megastructure in post-apocalyptic worlds. Pipes may contain valves that determine if they are full or empty. If they carry a dangerous substance like superheated steam their destruction may lead to the release of this hazard. In more playful worlds they may function like waterslides for those within them and may empty into storage pools or cisterns. Pipes may be found in the sewers, maintenance tunnels, and industrial areas.