Here are some cheats and tips for the game Spongebob Squarepants: Revenge of the Flying Dutchman.
Jelly fishing gear costume:
At the Krusty Krab, body slam the target. A tent will
appear and you will have the jelly fishing gear costume.
Mermaid man costume:
In downtown (construction site), deliver Krabby Patties
to Patrick and he will give it to you.
Reep blower costume:
In Jelly Fish Fields, win the 100 jelly fishing contest.
Your prize will be the Reep Blower costume.