ae91fae9_trols___Official_Terraria_Wiki__Notes
[Action] Left Thumbstick down [Effect] Down [Notes] 
Makes the character drop down when standing on a Wood Platform. Allows the character to go underwater (when using a Water Walking Potion, Water Walking Boots, Obsidian Water Walking Boots, or Lava Waders). Makes character climb down rope.
Game controls - Official Terraria Wiki
Notes