Bianco Hills
Bianco Hills is a hilly, countryside region in the center of Isle Delfino, found northwest of Delfino Plaza. It consists of the Windmill Village inhabited by Piantas, the upper hilly area, and a large lake. The centerpiece of this area is the very large windmill, which is located at the end of the lake. During Mario's travels to Isle Delfino, much of Bianco Hills was, like other regions of Isle Delfino, covered in disgusting Goop. Of course, Mario got rid of the nasty graffiti with FLUDD. Bianco Hills is where Mario also first battled the infamous Petey Piranha – first they battle inside of the windmill, the next time they fight in the village.
The entry to Bianco Hills requires 1 Shine Sprite from Delfino Airstrip.
Trivia
Interestingly, "Bianco" is Italian for "white", so the name translates to "White Hills".