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]x5.
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 |
| Level | Normal password | Unlimited air |
| The Undercaves | AAAAAAAA | LEVELSCT |
| The Vents | AANNAANN | |
| The Lagoon | NDRBRIKR | SHARKFIN |
| Ridge Water | HYAUGFLV | |
| Open Ocean | FNCQWBMT | KHDBVRIS |
| Ice Zone | DWFFZBMV | XRGQXRIX |
| Hard Water | ANANANAN | MAGLXRLM |
| Cold Water | MCLFRQLW | LNXHXRLB |
| Jurassic Beach | MDEBRCBO | |
| Pteranodon Pond | JNXFRCBS | |
| Origin Beach | AAAANNNN | |
| Island Zone | NNNNAAAA | DVJLURIC |
| Deep Water | EILQOQLC | OEWSURLC |
| The Marble Sea | XAKUQQLS | |
| The Library | FDGXQQLC | |
| Deep City | AANNNNAA | |
| City of Forever | DETSWCIY | |
| Trilobite Circle | DETSWCIY | |
| Dark Water | NNAANNAA | |
| Deep Water 2 | EQAAKNLC | |
| City of Forever 2 | ZBPIGPLD | FIVEPODS |
| The Tube | KUVEKMLK | |
| The Machine | NNNNNNNN | ECCOFMLY |
| The Last Fight | KNLMLMLC | |
Note: Enter "LIFEFISH" as a password to begin a new game with unlimited air.
Unlimited lives
Enter "NIHPLODS" as a password.