Pro Action Replay Codes:
Infinite Health - 00C249:08 -Rid
Infinite Lives - 00C24A:04 -Rune
Have All Mer-People Saved - 00C248:00 -Rune
Infinite Stars - 00C216:99 -Rune
Infinite Keys - 00C24B:09 -Rune
Infinite Sword-Fish - 00C201:09 -Rune
Infinite Yellow-Blue Fish - 00C1FD:09 -Rune
Infinite Red Crabs - 00C1FF:09 -Rune
Invulnerability - 00C9AD:0E

Game Genie Codes:
Invulnerability - 005-F99-7F4
Infinite lives - 006-109-19E
Collect 1 polyp to find exit - AF5-AA9-19E
Start with 3 lives - 027-4AF-F7A
Start with 8 lives - 077-4AF-F7A
Start with 10 lives - 097-4AF-F7A
Start with 26 lives - 197-4AF-F7A
Start with 51 lives - 327-4AF-F7A
Start with 99 lives - 627-4AF-F7A
Infinite keys - 005-039-E6E