Before you drop down to fight the soon-to-be Naval Piranha, hit the Piranha Plant with a yarn ball. Kamek will fly in and say, "OH MY! That's... GAH! It's been fun, but it's time for you to become Yoshi sushi! Hee hee hee!" This is a reference to the trick in Super Mario World 2: Yoshi's Island where you can bypass the Naval Piranha boss fight by hitting the plant with an egg before Kamek appears. Instead of casting his spell, Kamek simply says "OH, MY!!!" and flies away. In Yoshi's Woolly World, however, you'll still have to fight Naval Piranha.

Collect all the Flowers in Worlds 1 through 6 to open World Star-S on Craft Island.