Underground theme

Stages, levels, or locations with an underground theme are areas that take place underground. It is one of the reoccuring themes of the Mario series and one of the most common ones.

Other Traits and Features
One of the main features of underground-themed stages is that the stage takes place under certain levels and areas. Underground stages tend to follow other types of stages most notably plains-themed stages. Underground-themed stages can also associate with almost all other types of stages except for sky-themed stages for obivious reasons. Also, at most times, a stage will start out on the plains and the player then has to enter a Warp Pipe in order to get to the underground stage.

Underground-themed stages can have an assortment of enemies but one of the most common and reoccuring ones are Buzzy Beetles. These enemies tend to crawl on the top of the ceiling and then attempt to ram into the player. The main common enemies such as Goombas, Koopa Troopas, and Piranha Plants are also very common in underground-themed stages.

As for hazards, almost any time of hazard can occur within underground-themed stages. However, the most common hazard, like with sky-themed stages, are bottomless pits. Bottomless pits tend to be near where the player has to jump over them from platform to platform.

Examples

 * World 1-2 (Super Mario Bros.) - Super Mario Bros.
 * Kero Sewers - Super Mario RPG: Legend of the Seven Stars (also underwater theme)
 * Pipe Vault - Super Mario RPG: Legend of the Seven Stars