Ecco The Dolphin

Invincibility:
Hold A + Start when the name of the level appears. Release the buttons and press Start when the level is ready for game play.

No background music:
Pause game play and press A(5).

Cheat mode:
Turn Ecco to the left or right. Pause game play when Ecco is facing the screen. Press Right, B, C, B, C, Down, C, Up. A cheat menu with stage number, sound select, music tempo, message number, unlimited life, teleporter coordinate options will appear.

Level select:
Enter PLEASE** as a password, where ** represents one of the following two letter entries.

Level Suffix:
Ice Zone - EE
Island Zone - FF
Pteranadon Pond - GG
City of Forever - HH
Under Caves - II
Deep City - KK
Last Fight - OO
Origin Beach - QQ
Marble Sea - UU
Open Ocean - WW
Ridge Water - ZZ

Killer sonar:
Enter a level password with unlimited air. Press A + B during game play to kill all enemies on sonar.

Unlimited lives:
Enter NIHPLODS as a password.

Turn Background Music Off:
Pause during the game and Press A.