Cheat mode:
Turn Ecco to the left or right until he faces the screen. Press A, B, C, B, C, A, C, A, B to display a cheat menu with level select, sound test, and invincibility options.

Invincibility:
Turn Ecco to the left or right until he faces the screen. Press A, B, Right, A, C, A, Down, A, B, Right, A. The remaining health and air will disappear to confirm correct code entry. Ecco will be invincible with unlimited health and air.

Aqua Tubeway secret level:
Enter KJBBCHZA as a password. Nothing special will happen when you finish this level. Story-wise, it is are in-between the regular levels. Note: Using this password may prevent you from getting a secret password when you finish the City Of Forever level. Since the game will record if any cheats have been used, it is recommended that they be used after the game has already been completed.

Maze Of Stone secret level:
Enter ESKNPQXA as a password. Nothing special will happen when you finish this level. Story-wise, it is are in-between the regular levels. Note: Using this password may prevent you from getting a secret password when you finish the City Of Forever level. Since the game will record if any cheats have been used, it is recommended that they be used after the game has already been completed.

New Machine secret level:
Enter IPFHTCIA as a password. Nothing special will happen when you finish this level. Story-wise, it is are in-between the regular levels. Note: Using this password may prevent you from getting a secret password when you finish the City Of Forever level. Since the game will record if any cheats have been used, it is recommended that they be used after the game has already been completed.

View end sequence:
Enter CEWSXKPA as a password.

Expert mode:
Break the two shells that are above you in the starting area. Swim through the newly revealed tunnel for a harder version of the game.

Level	Normal	Hard
Crystal Springs	UEPMCVEB	WPHSAAFB
Gateway	KDCGTAHB	QKLLFPHB
Fault Zone	OZUNSKZA	CRNPTFZA
Big Water	QQCQRDRA	YCBXONIA
Two Tides	KDKINTYA	QUKGZZYA
Deep Ridge	UXQWJIZD	UPODMUQD
Skyway	SZXHCLDB	MCMBPJDB
The Hungry Ones	WBQQHMUE	YOHVUVLE
Sky Tides	OZWIDLDB	OZMRKIDB
Secret Cave	CHGTEYZE	SPKHKISE
Tube Of Medusa	QSJRYHZA	ODFADPYA
Lunar Bay	QYSMHZZE	WTHXKISE
Skylands	MULXRXEB	WXRDJYEB
Black Clouds	CLOCVFZE	USKIKDOE
Fin To Feather	YCPAWEXA	UQTFBRXA
Gravitor Box	UIXBGYWXE	WNQWZMME
Eagle's Bay	YCJPDNDB	QSNVMMDB
Globe Holder	SBFPWWJE	MIPGDOME
Asterite's Cave	AOJRDZWA	EGAQRVXA
Dark Sea	MXURVMLA
Four Islands	UOYURFDB	CZVQNHCB
Vortex Queen	IKIMTBPA	OOSFBXAA
Sea Of Darkness	UQZWIIAB	WFMYIDAB
Home Bay	CSNCMRUA	QNSGAPGA
Vents Of Medusa	MMVSOPBB	SHWZZNBB
Moray Abyss	IMCDSAHB	YCFSBRAB
The Eye		AGNEXBTE
Fish City		WKGETHCA
City Of Forever		WQHFTZHA
Epilogue	CEWSXKPA	AXBGKHBA
"Secret'"		AVQJTCBA