The Underground

The Underground is a playing field made out of metal in Mario Smash Football and Mario Strikers Charged Football. The stadium was funded by Wario and Waluigi. As its name implies, it is located several stories underground. In the store demo mode of Mario Smash Football, The Underground was the only unlocked field.

According to the Japanese Mario Smash Football site, it is located underneath "a certain city", possibly meaning Diamond City. The Capacity is 35,000; it is the Star Cup's special field.