Press Right, B, C, B, C, Down, C, Up while the game is paused and Ecco is facing the screen. To get Ecco to face the screen, turn him left or right and pause midway through the turn.
The Super Cheat Menu activates Everything from Sound Tests to Level Select. First, Move Ecco from Left to Right and Pause the Game when He Faces the Camera, Then Enter Right, 1, 2, 1, 2, Down, 2, Up.
Ecco the Dolphin Level passwords:
