Hello,

I am looking to identify a cartoon from 2004 to 2006...
The hero's has lived inside a whale and have the ability to turn into water droplets to pass unnoticed. With them there was also a mermaid... an episode where it was about Archimedes and has helped him defend his city against an attack...
Thank you!
This is not The Marvelous Misadventures of Flapjack

Resolved: Under Neptune's Flag [Pod Vlajkou Neptuna] (CZ, 1997)

Glad you found it! I spent quite a bit of time trying to figure it out... well done!