Depth Chargers
From Starfy Wiki
Depth Chargers (Japanese: もくって ゴーゴッゴー, Mokutte Go GoGo is a minigame in The Legendary Starfy. The goal is to dive deeper into the water than any other player. Starfy will dive at speeds based upon how fast the player moves the stylus back and forth across the top and bottom of the touch screen.
Instructions
"Slide the stylus back and forth to dive deeper and deeper! How far down can you go?"