River Twygz

The River Twygz is a subsection of the Underwhere in Super Paper Mario. It is evidently filled with the tears of evildoers that somehow give it a purple color. Charold will ferry the player across the river for 4 coins, but it is not required. The river is inhabited by Underhands, invincible, skeletal hands that will damage Mario. Near the bottom of the river, the river turns deep purple, and the music becomes eerie and distorted, filled with strange shrieks and moans. Before the events of Chapter 7, Luigi fell in the River Twygz. While he managed to get out of it, he was severely shaken from his experiences in it. Mario descends into the river in search of him.

Trivia

 * The name of the river is a play on the River Styx (commonly pronounced "sticks"), a similar river in the Greek Underworld.